WO2004084256A1

WO2004084256A1 - Low-pressure mercury vapor discharge lamp, and system of connected such lamps

Info

Publication number: WO2004084256A1
Application number: PCT/IB2004/050262
Authority: WO
Inventors: Wilhelmus M. Hellebrekers; Willem J. Van Den Bogert
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2003-03-20
Filing date: 2004-03-17
Publication date: 2004-09-30

Abstract

A low-pressure mercury vapor discharge lamp has a light-transmitting discharge vessel (10) having primary end portions (11; 11'). The discharge vessel encloses, in a gastight manner, a discharge space (13) provided with a filling of mercury and a rare gas. Electrodes (20; 20') are arranged at each primary end portion. Primary current-supply conductors (30, 31; 30', 31') extend from the electrodes through the primary end portions to outside the discharge vessel. The discharge vessel is contained in a light-transmitting tubular lamp envelope (1) having at least one secondary end portion (35). A circuit assembly (15) is contained in the lamp envelope coupled to the electrodes via the primary current-supply conductors. The circuit assembly is provided with secondary current-supply conductors (40, 41) issuing through the secondary end portion to the exterior of the lamp envelope. The discharge lamp according to the invention can be connected directly to the mains voltage.

Description

LOW-PRESSURE MERCURY VAPOR DISCHARGE LAMP, AND SYSTEM OF CONNECTED SUCH LAMPS

The invention relates to a low-pressure mercury vapor discharge lamp comprising a light-transmitting discharge vessel having primary end portions the discharge vessel enclosing, in a gaslight manner, a discharge space provided with a filling of mercury and a rare gas, 5 an electrode being arranged at each primary end portion in the discharge space for maintaining a discharge in the discharge space.

The invention also relates to a system comprising at least a first and a second low-pressure mercury vapor discharge lamp according to the invention.

In mercury vapor discharge lamps, mercury constitutes the primary component 10 for the (efficient) generation of ultraviolet (UV) light. A luminescent layer comprising a luminescent material (for example, a fluorescent powder) may be present on an inner wall of the discharge vessel to convert UV to other wavelengths, for example, to UV-B and UV-A for tanning purposes (sun panel lamps) or to visible radiation for general illumination purposes. Such discharge lamps are therefore also referred to as fluorescent lamps. The 15 discharge vessel of low-pressure mercury vapor discharge lamps is usually tubular and circular in section.

Low-pressure mercury vapor discharge lamps of the type described in the opening paragraph are well known in the art. A drawback of the use of the known low- pressure mercury vapor discharge lamp is that the discharge lamp cannot be connected 20 directly to the mains voltage.

It is an object of the invention to eliminate the above disadvantage wholly or partly. According to the invention, a low-pressure mercury vapor discharge lamp according to the invention is characterized in that the discharge vessel is contained in a light-transmitting tubular lamp envelope 25 having at least one secondary end portion, and a circuit assembly is contained in the lamp envelope coupled to the electrodes via the primary current-supply conductors, the circuit assembly being provided with secondary current-supply conductors issuing through the secondary end portion to the exterior of the lamp envelope. By integrating the circuit assembly in the low-pressure mercury vapor discharge lamp, the discharge lamp can be connected directly to the mains voltage. The known low-pressure mercury vapor discharge lamp is normally provided with two current- supply conductors at each side of the discharge lamp. These four current-supply conductors are connected to the circuit assembly (provided e.g. in a lamp fixture), said circuit assembly being connect to the mains voltage. This manner of wiring an (electrically) connecting takes a lot of space and reduces the applicability of discharge lamps.

Space requirements for low-pressure mercury vapor discharge lamps according the invention are reduced. In addition, the applicability of low-pressure mercury vapor discharge lamps is improved.

Because of the circuit assembly being integrated in the lamp envelope of the low-pressure mercury vapor discharge lamp, the number of electrical connections issuing from the lamp envelope can be reduced to only two. According to a preferred embodiment, the low-pressure mercury vapor discharge lamp according to the invention is characterized in that the lamp envelope of the low-pressure mercury vapor discharge lamp is provided with only one secondary end portion at one of the sides of the lamp envelope. In this manner a so- called single-ended TL lamp is provided with integrated circuit assembly.

Because the number of electrical connections issuing from the lamp envelope is reduced from four to two for the low-pressure mercury vapor discharge lamp according to the invention, low-pressure mercury vapor discharge lamps can be coupled to each other in a new manner. According to a preferred embodiment of the low-pressure mercury vapor discharge lamp, the lamp envelope is provided with a first secondary end portion and a second secondary end portion at adjacent sides of the lamp envelope, the first secondary end portion being provided with a first and a second male electrical connection means, and the second secondary end portion being provided with a first and a second female electrical connection means.

Preferably, the first male electrical connection means is electrically connected to the first female electrical connection means and the second male electrical connection means is electrically connected to the second female electrical connection means. This enables coupling of several low-pressure mercury vapor discharge lamps. During operation, only one of the low-pressure mercury vapor discharge lamp is connected to the mains voltage. The invention is not limited to the use of "male" or "female" electrical connection means; the wording "male" and "female" are only employed to indicate a manner of connecting the low-pressure mercury vapor discharge lamps. In addition, the "male" electrical connection means are usually provided in the well-known form of contact pins, the "female" electrical connection means can be brought in an engaging relationship with the "male" electrical connection means for realizing electrical (and mechanical) interconnection.

In the above-described manner a plurality of low-pressure mercury vapor discharge lamps can be coupled to each other. To this end in a system of at least a first and a second low-pressure mercury vapor discharge lamp the male electrical connection means of the first low-pressure mercury vapor discharge lamp is connected to the female electrical connection means of the second low-pressure mercury vapor discharge lamp.

The lamp envelope may have various lengths and a variety of shapes. To this end, a preferred embodiment of the low-pressure mercury vapor discharge lamp according to the invention is characterized in that the lamp envelope has various lengths and/or is shaped in a longitudinal form and/or bend form.

These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter. In the drawings:

Fig. 1 is a cross-sectional view of an embodiment of the low-pressure mercury- vapor discharge lamp in accordance with the invention in longitudinal section; Fig. 2 shows an alternative embodiment of the low-pressure mercury vapor discharge lamp according to the invention;

Fig. 3 A, 3B and 3C shows a plurality of systems of various interconnected low-pressure mercury vapor discharge lamp with various shapes according to the invention, and Fig. 4 shows a detail of an embodiment of the low-pressure mercury vapor discharge lamp according to the invention.

The Figures are purely diagrammatic and not drawn to scale. Notably, some dimensions are shown in a strongly exaggerated form for the sake of clarity. Similar components in the Figures are denoted as much as possible by the same reference numerals.

Figure 1 shows a low-pressure mercury- vapor discharge lamp comprising a glass discharge vessel 10 having a tubular portion, which discharge vessel 10 transmits radiation generated in the discharge vessel 10 and is provided with a first primary end portion 11 and a second primary end portion 11'. In this example, the discharge vessel 10 has a length Ldv of 120 cm and an inside diameter D_m of 24 mm. The discharge vessel 10 encloses, in a gaslight manner, a discharge space 13 containing a filling of mercury and an inert gas mixture comprising for example argon. The side of the tubular portion 11 facing the discharge space 13 can be provided with a protective layer (not shown in Figure 1). In fluorescent discharge lamps, the side of the discharge vessel 10 facing the discharge space 13 is coated with a luminescent layer 14 which includes a luminescent material (for example a fluorescent powder) which converts the ultraviolet (UV) light generated by fallback of the excited mercury into (generally) visible light. In Figure 1 means for maintaining a discharge in the discharge space 13 are electrodes 20; 20' arranged in the discharge space 13, said electrodes 20; 20' being supported by the primary end portions 11; 11'. The electrode 20; 20' is a winding of tungsten covered with an electron-emitting substance, normally a mixture of barium oxide, calcium oxide and strontium oxide. Primary current-supply conductors 30, 31'; 30', 31' extending from the electrodes 20; 20', respectively, pass through the primary end portions 11; 11' and issue to outside the discharge vessel 10. The primary current-supply conductors 30', 31 ' may be positioned against the outside the discharge vessel 10.

In the embodiment of the low-pressure mercury vapor discharge lamp according to the invention as shown in Figure 1, the discharge vessel 10 is contained in a light-transmitting tubular lamp envelope 1 having one secondary end portion 35. In addition, a circuit assembly 15 is contained in the lamp envelope 1, said circuit assembly 15 being coupled to the electrodes 20; 20' via the primary current-supply conductors 30, 31; 30', 31'. Preferably, the circuit assembly 15 is provided in the vicinity of the secondary end portion 35.

In Figure 1, the circuit assembly 15 is provided with secondary current-supply conductors 40, 41 issuing through the secondary end portion 35 to the exterior of the lamp envelope 1. The secondary end portion 35 is also addressed to as lamp cap. The secondary current-supply conductors 40, 41 are electrically connected to contact pins 45; 46. Because the circuit assembly 15 is integrated in the low-pressure mercury vapor discharge lamp, the contact pins 45; 46 are, in operation, directly connected to the mains voltage. The embodiment of the low-pressure mercury vapor discharge lamp according to the invention as shown in Figure 1 is a single ended TL lamp with integrated circuit assembly. In contrast to the known low-pressure mercury vapor discharge lamps only two electrical connections issue from the lamp envelope. The low-pressure mercury vapor discharge lamp according to the invention can be directly connected to the mains voltage. In a preferred embodiment of the low-pressure mercury vapor discharge lamp according to the invention, the lamp envelope 1 is provided a diffuser 2 . Such a diffuser largely improves the uniformity of the light distribution which in operation emanates from the low-pressure mercury vapor discharge lamp. In addition, it diminishes the view to the inside of the lamp envelope 1 where the discharge vessel 10, the circuit assembly 15 and the wiring are located. Suitable materials for the diffuser 24 are aluminum powder, aluminum oxide and the commercially available Voncoat.

Figure 2 shows an alternative embodiment of the low-pressure mercury vapor discharge lamp according to the invention comprising a glass discharge vessel 10 provided with a first primary end portion 11 and a second primary end portion 11 '. In Figure 2 electrodes 20; 20' arranged in the discharge space 13, said electrodes 20; 20' being supported by the primary end portions 11; 11'. Primary current-supply conductors 30, 31'; 30', 31' extending from the electrodes 20; 20', respectively, pass through the primary end portions 11 ; 11 ' and issue to outside the discharge vessel 10. In the example of Figure 1 , the discharge vessel 10 is contained in a light-transmitting tubular lamp envelope 1 having a first secondary end portion 35 and a second secondary end portion 45 at adjacent sides of the lamp envelope 1. The first secondary end portion 35 is provided with a first and a second male electrical connection means 45; 46. In addition, the second secondary end portion 45 is provided with a first and a second female electrical connection means 50; 51. In Figure 2, the first male electrical connection means 45 is electrically connected to the first female electrical connection means 50 via the first secondary current- supply conductor 40 and a further first secondary current-supply conductor 40'. In addition, the second male electrical connection means 46 is electrically connected to the second female electrical connection means 51 via the second secondary current-supply conductor 41 and a further second secondary current-supply conductor 41'. This enables coupling of several low- pressure mercury vapor discharge lamps. During operation, only one of the low-pressure mercury vapor discharge lamp is connected to the mains voltage.

In order to further improve the uniformity of the light distribution emitted by the low-pressure mercury vapor discharge lamp, a preferred embodiment of the low-pressure mercury vapor discharge lamp according to the invention is characterized in that the circuit assembly 15 is divided in a first and a second subassembly (not shown in Figure 2), the first subassembly being positioned in the vicinity of the first secondary end portion 35 and the second subassembly being positioned in the vicinity of the second secondary end portion 45. By way of example, the first subassembly may contain the high-frequency part of the circuit assembly 15 and the second subassembly may contain the low-frequency part of the circuit assembly 15.

The invention also relates to a system comprising at least a first and a second low-pressure mercury vapor discharge lamp according to the invention. The lamp envelope of the first and/or the second low-pressure mercury vapor discharge lamp can have various lengths and/or can be shaped in a longitudinal form and/or bent form. Figure 3A, 3B and 3C shows a plurality of systems of various interconnected low-pressure mercury vapor discharge lamp with various shapes according to the invention. For clarity reasons, Figure 3A, 3B and 3C only show the lamp envelopes, not the interior of the discharge lamps. Figure 3 A shows two longitudinally shaped low-pressure mercury vapor discharge lamps 100, 101. The female electrical connection means of the first low-pressure mercury vapor discharge lamp 100 are connected to the male electrical connection means of the second low-pressure mercury vapor discharge lamp 101. The arrows in Figure 3 A indicate how the discharge lamps 100, 101 are interconnected. In addition, mains connection means 110 are shown. In operation, a high number of low-pressure mercury vapor discharge lamps can be connected together to a single mains voltage supply.

Figure 3B shows three low-pressure mercury vapor discharge lamps 200, 201, 202. The discharge lamps with reference numerals 200 and 202 are longitudinally shaped but of different length. The discharge lamp with reference numeral 201 is shaped in the form of a "knee". The female electrical connection means of the first low-pressure mercury vapor discharge lamp 200, 201 are connected to the male electrical connection means of the second low-pressure mercury vapor discharge lamp 201, 202. The arrows in Figure 3B indicate how the discharge lamps 200, 201, 202 are interconnected. By employing various lengths and shapes three-dimensional networks of low-pressure mercury vapor discharge lamps can be build easily.

Figure 3C shows two low-pressure mercury vapor discharge lamps 301, 302. The discharge lamp with reference numerals 301 has a bent form. The discharge lamp with reference numeral 302 is longitudinally shaped. The female electrical connection means of the first low-pressure mercury vapor discharge lamp 301 are connected to the male electrical connection means of the second low-pressure mercury vapor discharge lamp 302. The arrows in Figure 3C indicate how the discharge lamps 301, 302 are interconnected. By employing various lengths and shapes three-dimensional networks of low-pressure mercury vapor discharge lamps can be build easily. Figure 4 shows a detail of an embodiment of the low-pressure mercury vapor discharge lamp according to the invention. The electrode 20 is arranged in a primary end portion 11 which also contains an amalgam 17. Part with reference numeral 19 of the primary end portion 11 fits into the circuit assembly 15 for positioning the discharge vessel 10 in the lamp envelope. In an alternative embodiment spacers between the outer wall of the discharge vessel and the inner wall of the lamp envelope are used to position the discharge vessel in the lamp envelope.

A preferred embodiment of the system of at least a first and a second low- pressure mercury vapor discharge lamp according to the invention is characterized in that the first and a second low-pressure mercury vapor discharge lamp are driven by a pulse signal for switching on an off the first and the second low-pressure mercury vapor discharge lamp independent of each other. This provides a plurality of lighting possibilities.

The low-pressure mercury vapor discharge lamps in the system of low- pressure mercury vapor discharge lamps can be used to build 3 -dimensional networks of discharge lamps. This renders the system of low-pressure mercury vapor discharge lamps very suitable for home and office applications.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS:

1. A low-pressure mercury vapor discharge lamp comprising a light-transmitting discharge vessel (10) having primary end portions (11; 11') the discharge vessel (10) enclosing, in a gastight manner, a discharge space (13) provided with a filling of mercury and a rare gas, an electrode (20; 20') being arranged at each primary end portion (11; 11 ') in the discharge space (13) for maintaining a discharge in the discharge space (13), primary current-supply conductors (30, 31; 30', 31') extending from the electrodes (20; 20') through the primary end portions (11 ; 11 ') to outside the discharge vessel (10), characterized in that the discharge vessel (10) is contained in a light-transmitting tubular lamp envelope (1) having at least one secondary end portion (35), and a circuit assembly (15) is contained in the lamp envelope (1) coupled to the electrodes (20; 20') via the primary current-supply conductors (30, 31; 30', 31'), the circuit assembly (15) being provided with secondary current-supply conductors (40, 41) issuing through the secondary end portion (35) to the exterior of the lamp envelope (1).

2. A low-pressure mercury vapor discharge lamp as claimed in claim 1, characterized in that the lamp envelope (1) is provided with a first secondary end portion (35) and a second secondary end portion (45) at adjacent sides of the lamp envelope (1), the first secondary end portion (35) being provided with a first and a second male electrical connection means (45; 46), and the second secondary end portion (45) being provided with a first and a second female electrical connection means (50; 51).

3. A low-pressure mercury vapor discharge lamp as claimed in claim 2, characterized in that the first male electrical connection means (45) is electrically connected to the first female electrical connection means (50) and the second male electrical connection means (46) is electrically connected to the second female electrical connection means (51).

4. A low-pressure mercury vapor discharge lamp as claimed in claim 2, characterized in that the circuit assembly (15) is divided in a first and a second subassembly, the first subassembly being positioned in the vicinity of the first secondary end portion (35) and the second subassembly being positioned in the vicinity of the second secondary end portion (45).

5. A low-pressure mercury vapor discharge lamp as claimed in claim 1, characterized in that the lamp envelope (1) is provided with only one secondary end portion (35) at one of the sides of the lamp envelope (1).

6. A low-pressure mercury vapor discharge lamp as claimed in claim 5, characterized in that the circuit assembly (15) is provided in the vicinity of the secondary end portion (35).

7. A low-pressure mercury vapor discharge lamp as claimed in claim 1, 2,or 5, characterized in that the lamp envelope (1) has various lengths and/or is shaped in a longitudinal form () and/or bend form ().

8. A low-pressure mercury vapor discharge lamp as claimed in claim 1, 2,or 5, characterized in that the lamp envelope (1) is provided a diffuser (24).

9. A system of at least a first and a second low-pressure mercury vapor discharge lamp (100, 101; 200, 201, 202; 301, 302) as claimed in claim 2, the female electrical connection means of the first low-pressure mercury vapor discharge lamp ( 100; 200, 201 ; 301) being connected to the male electrical connection means of the second low-pressure mercury vapor discharge lamp (101; 201, 202; 302).

10. A system of at least a first and a second low-pressure mercury vapor discharge lamp (200, 201, 202; 301, 302) as claimed in claim 9, characterized in that the lamp envelope of the first and/or the second low-pressure mercury vapor discharge lamp (200; 201, 202; 301, 302) has various lengths and/or is shaped in a longitudinal form (200, 202; 302) and/or bent form (201; 301).

11. A system of at least a first and a second low-pressure mercury vapor discharge lamp as claimed in claim 9, characterized in that the first and a second low-pressure mercury vapor discharge lamp are driven by a pulse signal for switching on an off the first and the second low-pressure mercury vapor discharge lamp independent of each other.