A LAMP DEVICE AND A LAMP TUBE AS WELL AS A METHOD OF REGULATING THE LAMP DEVICE

Abstract: The present invention relates to a lamp device comprising a lamp tube (1), such as a UV intermediate pressure lamp, which is arranged in an outer globe (2) mounted in a socket (4). The end area of the outer globe (2) is enclosed by sealing means (5, 6, 7, 8, 9) for ensuring mutual vacuum-tight mounting of socket (4) and outer globe (2). It is further possible to re-use most of the elements in the lamp. Merely the worn down lamp tube must be replaced. This is particularly important when using a lamp device according to the invention in a UV system for photochemical water purification. The lamp device may additionally comprise a regulation device for regulating the intensity of electromagnetic radiation in selected wavelengths, said regulation device comprising means for temperature measurement of an inactive gas in the outer globe and means for regulating the tube voltage of the lamp.

Description: A lamp device and a lamp tube as well as a method of regulating the lamp device The present invention relates to a lamp device comprising a lamp tube, such as an UV lamp which is arranged in an outer globe having at least one opening closed by a socket through which there are electrical connections to the lamp tube. The invention also relates to a lamp tube for the lamp device and to a method of regulating it. Today, lamp devices for many purposes are known. Thus, for use in ultraviolet irradiation, it is known to use a mercury-dosed lamp arranged inside an outer globe and sealed in a socket, which is exteriorly provided with threads in order to be screwed into a corresponding socket for mounting. Such UV intermediate pressure lamps are used inter alia in UV systems where it is important that the intensity of the ultraviolet light is sufficiently energy-rich, and that the wavelength of the radiation is reasonably uniform during the service life of the lamp. Such UV intermediate pressure lamps typically have a service life of about 1-3000 hours, following which they must be re- placed. When a lamp is dead, and it has been replaced, it is thrown out today. This disposal constitutes an environmental problem, as the lamps contain expensive and envi- ronmentally toxic materials. Such a disposal may moreover be considered to be a waste of resources. Pure quartz glass or synthetic quartz glass is expensive and cannot be molten down, as the quartz evaporates before it melts, and as it is actually just the lamp tube which has been worn down and has become leaky, and thus causes the entire lamp to be discarded. The lamp tube is dosed with mercury and/or other metals. Further, an inactive gas, such as argon or the like, has been added. In this connection, a distinction is made be- tween low and intermediate pressure lamps. The lamp tube may moreover be mounted in an outer globe. These lamps are optimized to yield as much ultraviolet light as possible. Additional focus for the further de- velopment of UV lamps is the lamp power, at the same time as the lamps are made smaller and manufactured with a smaller diameter, in particular when low pressure lamps are involved. These trends, however, make the lamps more sensitive to temperature. It has thus been found that fluctuations in the surface temperature of a lamp result in a reduction in the service life and a great drop in the luminous efficacy. In the production of a UV low pressure lamp, the emission of the lamp is determined at a specific vapour pressure. In this connection, tests have shown that a change in the surface temperature of 5 °C relative to the ideal surface temperature of the lamp may result in a reduction in the ultraviolet light (the electromagnetic radiation) in the form of both UV light intensity and a change in the wavelengths of the light of 20%. This has turned out to be a problem in connection with UV lamps for disinfection of water, air as well as inactivation of bacteria, virus, etc. For intermediate pressure lamps in particular, the high working temperature has the result that the lamp gets leaky in the joint sooner or later, in case of lamps which are directly pressed together at the lamp ends in connection with the electrodes, whereby air and water vapours penetrate into the lamp. This is seen clearly, as the gas of the lamp gets yellow or black, and then the lamp goes out shortly afterwards. A too low temperature of the lamp may cause the ionization coating to be deposited (condensed) on the inner side of the quartz lamp glass. This is seen in that the ends of the lamp become silver-coloured. The correct surface temperature is particularly important to achieve in order to derive full benefit from the use of metal haiide lamps, which are UV lamps which have been metal-dosed to achieve electromagnetic radiation within a specific range of wavelengths. This has been found to be a problem e.g. in connection with UV lamps for photochemical processes where the wavelengths of the ultraviolet light may be decisive for the effect of the process relative to the individual substances. The most relevant system known in this connection is a regulation system in which the tube voltage of the lamp is controlled by a light meter. This regulation takes place in that when the light intensity decreases, this is registered by the light meter, which signals this to a control unit which then increases the tube voltage of the lamp in compensation. However, when the tube voltage is increased, also the surface temperature is increased, which may actually cause the light intensity to be decreased again and the tube voltage to be increased again, which has the effect that the regulation will then contribute to additionally impairing the luminous efficacy of the lamp. Furthermore, also the service life of the lamp is shortened by this. US-A-5 220 235 discloses a lamp device where, in the outer globe, air is circulated through a base for cool- ing. The UV radiation in the globe generates ozone which is extremely toxic, and which moreover degrades the lamp, e.g. the electrical terminals are oxidized. The outer globe is provided with a coating to retain harmful UV ra- diation, and is thus of another type than the one accord ¬ ing to the invention. Accordingly, the object of the invention is to provide a lamp device which overcomes the above-mentioned drawbacks of the known lamp types, just as the invention is intended to provide a longer service life for the lamp. Another object of the invention is to provide a system which gives the lamp tube a longer service life and a more constant luminous efficacy, both as regards light intensity and the wavelengths of the emitted electromag ¬ netic radiation. The invention comprises a lamp device of the type defined in the introductory portion of claim 1, in which the socket is composed of elements comprising a plug for closing an end opening in the outer globe, said plug having a part inserted into the globe and being connected with the lamp tube, and an outer part, and the outer part and the end area of the outer globe are enclosed by seal- ing means for ensuring mutual vacuum-tight mounting of the socket and the outer globe. With a lamp device according to the invention it is possible to re-use the socket of the lamp in a new lamp, when the first one is dead and otherwise has to be discarded in its entirety. The outer globe, which is typically a quartz glass tube, can also be cleaned and re-used in a new lamp device. The individual elements may thus be reused directly or after a cleaning, which means that it is only very few components which must be disposed of when the lamp is replaced. This provides an environmentally friendly solution as well as an economic saving in connection with the lamp replacement, as it is merely the lamp tube which has been worn down and must be replaced. As the outer globe is re-used, the invention can also make it economical to use an outer globe of the more at ¬ tractive, but also considerably more expensive sapphire glass. In connection with the sealing means for the socket it has been realized by the invention that it is possible to regulate the vacuum inside the outer globe. The sealing means moreover have the effect that the socket is vacuum-tight, which is important in particular when using a lamp device according to the invention in a UV filter for photochemical water purification. When, as stated in claim 3, the outer globe contains an inactive gas, e.g. nitrogen, argon, helium and xenon, and the gas in the globe is under vacuum, preferably about 500 mb, the wavelength of particularly the electromagnetic radiation, the UV light, from the lamp tube may be controlled. Also a long life of the lamp is achieved hereby. Another and important advantage is that when the outer globe is filled with inactive gas and sits freely in the air or is partly immersed into water, no ozone, which is harmful to the environment and is also a health hazard, can be formed by UV lamps with wavelengths < 190 nm. When, as stated in claim 4, the socket comprises a vacuum-tight valve in a channel, the outer globe, after co - pleted assembly, may be scavenged with an inactive gas and be evacuated in the same connection. When, as stated in claim 5, the part of the plug inserted into the outer globe is formed with ring-shaped barb flanges, preferably of FPM (fluorocarbon) or FFKM (perfluorocarbon) , the plug is prevented from displacing itself out of the outer globe once it has been pushed in. - The barb flanges are preferably dimensioned with an oversized diameter relative to the opening in the outer globe. The plug is made of an insulating material which is vacuum-tight, preferably aluminium ceramic oxide. When, as stated in claim 6, sensor means, such as means for temperature measurement, are passed through the plug " , so that the lamp device is prepared for temperature meas- urement inside the outer globe, the service life of the lamp may be prolonged considerably, it being thus possible to measure the temperature of the lamp tube indirectly and to control it, e.g. through regulation of the temperature, the pressure or the like of the gas in the outer globe. When, as stated in claim 7, the sealing means comprise a plurality of mounting elements, including clamping rings which are arranged externally on the socket when this is mounted in the outer globe, and this socket device may finally be coated with a rubber cap, an extremely tight and easily mountable assembly of the socket in a lamp device according to the invention is achieved. As stated in claim 8, the lamp device may be equipped with a regulation device comprising means for temperature measurement of the inactive gas and means for regulating the tube voltage of the lamp tube. When the lamp is regulated in response to the temperature of the inactive gas, an increase in the service life of the lamp is achieved according to the invention, just as uniformity in the electromagnetic radiation of the lamp (UV light) may be achieved, both as regards the emitted radiation energy and the emitted wavelengths of the radiation in the entire service life of the lamp. - A special use of a regulation device according to the invention is in connection with a so-called metal halide lamp which is made of aluminium ceramic oxide with a binder such as MgF or Li 2 F, which allows passage of the electromagnetic radiation in the lower UV range e.g. 100- 300 nm, where the lamp is dosed with special metals to provide a selected range of UV wavelengths. Such lamps are extremely sensitive to low temperature on the surface of the lamp tube, and it is therefore advantageous to use a regulation device according to the invention for a metal halide lamp for controlling the gas temperature in the outer globe. In an embodiment, which is defined in claim 9, the regulation device comprises a temperature sensor for measuring the temperature of the inactive gas, and the regulation means comprise a control unit capable of receiving temperature measurements from the temperature sensor and of regulating the tube voltage of the lamp to achieve a desired gas temperature. When measuring the temperature of the gas near the face which is to be temperature-controlled, it is possible to achieve a rapid and precise regulation of the surface temperature of the lamp tube. In an embodiment according to claim 10, a light meter, such as a UV sensor, is moreover connected to the control unit. This allows control of both parameters. However, in this case, the control unit is adapted such that the gas temperature measurements have the highest priority in the regulation. As stated in claim 11, the device may moreover be provided with a control unit which allows current control of the status of the lamp tube. With this addition, it is possible to output data and thereby currently monitor the -state of the lamp. In the embodiment defined in claim 12, the control unit is preferably provided with a temperature control of the inactive gas to prevent an unintentional change in the tube voltage of the lamp if the surface temperature of the lamp is below or above the ideal surface temperature ' . This puts a limit to the loading of the lamp, whereby the lamp will not be subjected to overloading, particularly if the voltage is regulated in steps. As stated in claim 13, the invention also relates to a lamp tube made of aluminium ceramic oxide with a binder such as MgF or Li 2 F which allows passage of electromagnetic radiation in the low UV range, e.g. in the range 100-300 nm. The invention moreover provides a method of regulating the radiation intensity of a lamp with a regulation device according to the invention, wherein the temperature of the inactive gas in the outer globe is measured and the tube voltage is regulated to achieve a desired sur- face temperature of the lamp tube, cf. claims 14-15. The invention will be described more fully below with reference to the accompanying drawing, in which fig. 1 shows an assembly drawing of a socket composed of elements for a lamp device according to the invention, and fig. 2 schematically shows a layout of a regulation device for a lamp device according to the invention. 12 P a t e n t C l a i m s 1. A lamp device comprising a lamp tube (1), such as a UV lamp, which is arranged in an outer globe (2) having at least one opening closed by a socket (4) through which there are electrical connections (10) to the lamp tube (1), c h a r a c t e r i z e d in that the socket (4) is composed of elements comprising a plug (3) for closing an end opening in the outer globe (2), said plug having a part (3") inserted into the outer globe (2) and being connected with the lamp tube (1), and an outer part (3'), and that this outer part (3') of the plug and the end area of the outer globe (2) are enclosed by sealing means (5, 6, 7, 8, 9) for ensuring mutual vacuum-tight mounting of the socket (4) and the outer globe (2) . 2. A lamp device according to claim 1, c h a r a c t e r i z e d in that the lamp tube (1) is made of alu- minium ceramic oxide with a binder such as MgF or Li 2 F which allows passage of electromagnetic radiation in the low UV range, e.g. in the range 100-300 nm. 3. A lamp device according to claim 1 or 2, c h a r - a c t e r i z e d in that the outer globe contains an inactive gas, e.g. nitrogen, argon, helium, xenon, and that a vacuum, preferably about 500 mb, exists in the outer globe (2) . 4. A lamp device according to claim 1 or 3, c h a r a c t e r i z e d in that the connections in the plug (3) comprise a channel (11), and that a vacuum valve (14) is arranged in the channel (11) for scavenging the outer globe and maintaining the desired vacuum, said valve be- ing closed when this has been reached. - Figure 1 shows a UV lamp according to the invention where a lamp tube 1 is mounted in an outer globe 2 of quartz glass which, at the top, has an opening closed by a socket 4 comprising a plug 3 which is partly inserted into the opening of the outer globe 2. The lamp is mounted via the socket 4 in a reception opening in a lamp holder or the like. The socket 4 comprises a plurality of mounting elements in the form of rings 6, 7 which are arranged in a water and air sealing manner around the opening of the outer globe 2 of quartz glass. A sealing cap 5, which closes the end of the outer globe in a vacuum sealing manner, is arranged exteriorly on the end of the outer globe 2 and the socket 4. Optionally, 0- rings may be embedded in the cap. It moreover exhibits two outer faces whose conicity corresponds to the conic- ity of the cooperating clamping ring 6 and the mounting ring 7, respectively. The sealing cap 5 is preferably made of a rubber material, and the clamping ring is preferably made of stainless steel or a similar corrosion resistant material. During assembly, the clamping ring 6 is wedged down between the mounting ring 7 and the sealing cap 5 in which the rest of the socket 4 is arranged. At least a portion of the outer side of the mounting ring 7 may be provided with threads for mounting in the reception opening. As will appear, the plug 3 consists of an outer part 3' and an insertion part 3" which is arranged in the opening of the outer globe 2 of quartz glass. The insertion part 3" is provided with a plurality of ring-shaped barb flanges 9 which counteract withdrawal once the plug 3 is mounted in the outer globe 2 of quartz glass. 10 The plug 3 is formed with channels 10, 10', 11 for various purposes. At least two connecting channels 10 are electrically connected to the lamp tube 1 (see figure 1). Further, there may be connecting channels 10' of the same type as the channels 10 for electrical connection. These additional connecting channels 10' may be used for ar ¬ ranging sensor means for e.g. temperature measurement in ¬ side the outer globe 2 of quartz glass, preferably of the inactive gas in the outer globe 2 near the surface of the lamp tube 1. Moreover, a valve channel 11, in which a vacuum valve 12 is seated, is provided in a preferred em ¬ bodiment of a lamp device according to the invention. A lamp device according to the invention provides consid- erable savings in connection with particularly UV lamps for photochemical process systems, since the service life may be expected to be prolonged from normally about 1- 3,000 hours up to 24,000 hours, and the state of the lamp tube may currently be controlled, and the lamp may be regulated, e.g. through temperature control of the inac ¬ tive gas in the outer tube. A lamp tube contains an inactive gas. It is provided with electrodes 15 at each end. In another aspect of the in- vention it is realized that the gas in the lamp tube 1 may be dosed with a halogen material, instead of mercury like today. The selection of dosing material depends on the purpose for which the lamp tube is to be used, it having been realized by the invention that a great light intensity in desired wavelengths of ultraviolet light may be achieved by suitable selection of material in the dosing. As dosing material, e.g. bromoxide, ferric oxide, mercury, amalgam and the like, metals/metal oxides as well as halogens may be mentioned. In case of halogens where the temperature may reach 1650 °C, which exceeds the melting temperature of quartz glass, use is made of

Claims: 11 lamp tubes of aluminium ceramic oxide with a binder such - as MgF or Li 2 F which allows passage of UV light in the low range, e.g. 100-300 n , it being intended that the lamp is as transparent as possible to avoid internal re- flection of photons. Figure 2 shows an electronic control unit 16 which, in the embodiment shown, is preferably a high frequency controllable switch mode ballast for controlling the lamp 17. The control unit is connected to a power supply 18 which is preferably a phase-compensated double rectifier with incorporated EMC filter. Adjacent the lamp 17 near the surface of the lamp, a tem- perature sensor 19 is arranged for measuring the inactive gas temperature. In the structure shown, this sensor 19 is connected to a signal amplifier 20 which amplifies the temperature measurement from the sensor 19 and sends the amplified signal to the control unit 16. In the embodiment shown, a UV light sensor 21, which preferably has a measurement range of 200 nm to 400 nm, is moreover arranged adjacent the lamp 17. The signal of the UV sensor is then amplified in a UV intensity ampli- fier 22 which sends the amplified UV signal further on to the control unit 16. The control unit 16 can regulate the lamp 17 by regulating the tube voltage of the lamp on the basis of the sig- nals fed to the unit 16. The control unit 16 may furthermore be connected to a control circuit 23 via which e.g. an operator can currently monitor the status of the lamp. 5. A lamp device according to any preceding claim, -c h a r a c t e r i z e d in that the part (3") of the plug (3) inserted into the outer globe (2) is formed with ring-shaped barb flanges (9) . 6. A lamp device according to any preceding claim, c h a r a c t e r i z e d in that sensor means, such as means for temperature measurement, are passed through the plug (3), so that the lamp is prepared for temperature measurement inside the glass tube (2), preferably of the inactive gas . 7. A lamp device according to any preceding claim, c h a r a c t e r i z e d in that the sealing means com- prise a plurality of mounting elements (5, 6, 7), including clamping rings (6) which enclose the plug (3) when this is mounted in the glass tube (2), and that this socket device (4) may finally be coated with a rubber cap (5) . 8. A lamp device according to any preceding claim, c h a r a c t e r i z e d in that it comprises a regulation device for regulating the intensity of the electromagnetic radiation in selected wavelengths and means for temperature measurement of the inactive gas and means for regulating the tube voltage of the lamp tube. 9. A lamp device according to claim 8, c h a r a c t e r i z e d in that the temperature measurement means comprise a temperature sensor (19) near the surface of the lamp tube, and that the regulation means comprise a control unit (16) capable of receiving temperature measurements from the temperature sensor and of regulating the tube voltage of the lamp to achieve a desired surface temperature. 10. A lamp device according to claim 9, c h a r a c t e r i z e d in that a light meter, such as a UV sensor (21), is connected to the control unit (16) . 11. A lamp device according to claim 9 or 10, c h a r a c t e r i z e d in that the device is provided with a control unit (23) which allows current control of the status of the lamp tube. 12. A lamp device according to claims 9-11, c h a r a c t e r i z e d in that the control unit (16) is provided with a temperature control to prevent a predetermined change in the tube voltage of the lamp if the ideal surface temperature of the lamp has been reached. 13. A lamp tube, c h a r a c t e r i z e d in that it is made of aluminium ceramic oxide with a binder such as MgF or Li 2 F which allows passage of electromagnetic radiation in the low UV range, e.g. in the range 100-300 nm. 14. A method of regulating the intensity of electromagnetic radiation in selected wavelengths from a lamp with a regulation device according to any preceding claim, c h a r a c t e r i z e d in that the temperature of the inactive gas is measured, and the tube voltage of the lamp is regulated to achieve a desired surface temperature of the lamp tube. 15. A method according to claim 14, c h a r a c t e r i z e d in that the gas temperature is measured near the surface of the lamp tube.

Inventors: KASS POVL, KASS, POVL
Applicants: KASS POVL, KASS, POVL
Application year: 1998
Main classification: H01J5
IPC codes: C02F1, H01J61