GERMICIDAL AMALGAM LAMP WITH TEMPERATURE SENSOR FOR OPTIMIZED OPERATION

Abstract

A germicidal UV amalgam lamp with an elongated tubular lamp body and at least two filaments located on opposite ends of the lamp body. The lamp body is hermetically sealed with a pinch-sealed portion at both opposite ends, confining a gas volume in which a gas discharge can be produced along a discharge path between the filaments. Each filament has two electrical connectors, each including an internal portion connected to the filament and pinch-sealed into the lamp body. Each connector also includes an external portion located outside the lamp body for electrical connection of the lamp to a controlled power supply. The pinch-sealed portion bears a socket with an electrical temperature sensor and at least two electrical connections mounted to the socket. The at least two electrical connections of the temperature sensor are connected in parallel to the electrical connectors of the filament.

Claims

1-17. (canceled)

18. A germicidal UV amalgam lamp comprising: an elongated tubular lamp body hermetically sealed at opposite ends with pinch-sealed portions, the body confining a gas volume, each pinch-sealed portion bearing a socket; at least two filaments located on the opposite ends of the lamp body within the gas volume and configured to produce a gas discharge along a discharge path between the filaments, each filament comprising two electrical connectors, each electrical connector including an internal portion connected to the filament and pinch-sealed into the lamp body, and an external portion located outside the lamp body and configured for electrical connection of the lamp to a controlled power supply; and an electrical temperature sensor mounted to each socket and having at least two electrical connections connected in parallel to the two electrical connectors of one or the filaments.

19. The germicidal UV amalgam lamp of claim 18, wherein the socket comprises a void and the temperature sensor is located inside the void.

20. The germicidal UV amalgam lamp of claim 19, wherein the temperature sensor is sealed into the void in a watertight manner.

21. The germicidal UV amalgam lamp of claim 18, wherein the connection of the temperature sensor to the filament is located inside the socket.

22. The germicidal UV amalgam lamp of claim 18, wherein the temperature sensor is a metal wire sensor.

23. The germicidal UV amalgam lamp of claim 22, wherein the metal wire sensor is a platinum wire sensor or a thermocouple.

24. The germicidal UV amalgam lamp of claim 18, wherein the temperature sensor is a semiconductor sensor.

25. The germicidal UV amalgam lamp of claim 24, wherein the semiconductor sensor is a PTC or NTC sensor.

26. The germicidal UV amalgam lamp of claim 18, wherein the temperature sensor is a bus-controlled sensor or a microcontroller.

27. A method of operating a germicidal UV amalgam lamp, comprising using a temperature sensor integrated into a socket adjacent a pinch-sealed end portion of the lamp to measure temperature of an end portion of the lamp.

28. The method of claim 27, comprising measuring the temperature with the temperature sensor before starting the lamp.

29. The method of claim 28, comprising selecting a lamp starting voltage or a lamp starting frequency dependent upon the temperature measured by the temperature sensor.

30. The method of claim 27, comprising electrically preheating a filament of the lamp before starting the lamp when the temperature measured by the temperature sensor is below a predetermined threshold value.

31. The method of claim 27, comprising not starting the lamp when the temperature measured by the temperature sensor is outside of a predetermined range or when the temperature sensor is unable to measure the temperature.

32. The method of claim 27, comprising terminating operation of the lamp if the temperature measured by temperature sensor is above a predetermined threshold value.

33. The method of claim 32, wherein the lamp is a member of a lamp group or array and the method comprises terminating operation of the lamp group or array as a whole when the temperature measured by temperature sensor is above the predetermined threshold value.

34. The method of claim 32, wherein the lamp is a member of a lamp group or array and the method comprises terminating operation of the lamp group or array as a whole when the temperatures measured by temperature sensors of two lamps of the lamp group or array both exceed the predetermined threshold value.

35. The method of claim 27, comprising using a lamp controller to estimate an amalgam temperature of the lamp based upon the temperature measured by temperature sensor.

36. The method of claim 35, further comprising basing the estimate of the amalgam temperature of the lamp on at least one other parameter in addition to the temperature measured by temperature sensor.

37. The method of claim 36, wherein the at least one other parameter comprises operating time of the lamp, electric power consumption of the lamp, or ambient temperature.

38. The method of claim 27, comprising controlling electric power supplied to the lamp dependent upon the temperature measured by the temperature sensor.

Description

[0024] Two preferred embodiments of the invention will be described in the following with reference to the drawings, in which

[0025] FIG. 1 shows one end portion of a germicidal UV lamp of the low pressure type with a temperature sensor in electrically parallel connection with the filament;

[0026] FIG. 2 shows an end portion of a germicidal UV lamp like in FIG. 1, but with a temperature sensor at another position in the socket; and

[0027] FIG. 3 shows the end portion of FIG. 2 in a more realistic perspective representation.

[0028] FIG. 1 shows one end portion 1 of a germicidal UV lamp 2. The lamp may be of the low-pressure mercury amalgam gas discharge type, which is widely in use in drinking water and wastewater disinfection installations.

[0029] The lamp 2 comprises a lamp body 3, which is made of technical quartz glass, because this material allows ultraviolet radiation down to 200 nm to pass through the material without significant absorption. The lamp body 3 encloses a hermetically sealed gas volume 4, which usually is filled with a noble gas at low pressure. The length of the lamp body 3 and the gas volume 4 may be between 0.1 m and 2 m, preferably between 1 m and 2 m.

[0030] The tubular lamp body 3 is hermetically sealed at both ends. The end 1 shown in FIG. 1 is sealed in a pinch-sealed portion 5, which essentially is a portion in which the lamp body 3 has been constricted and then pressed flat using an elevated temperature at which the material of lamp body 3 can be plastically deformed. The pinch-sealed portion 5 may be of the same material as the lamp body 3, so that a uniform tube of material can be used in the production process. The portion 5 can, however, also be made from another material like technical glass, which is fused to the lamp body 3 in order to allow plastic deformation at lower temperatures than would be necessary in the treatment of quartz glass.

[0031] Inside the pinch-sealed portion 5, there are electrical leads, namely a first electrically conducting wire 6 and a second electrically conducting wire 7. The wires 6 and 7 are sealed into the pinch-sealed portion 5 in a gas-tight manner. The wire 6 is connected to an external connecting pin 8, which is located outside the pinch-sealed portion 5 in order to be connected in a known manner, to a socket (not shown). Likewise, wire 7 is connected to a connecting pin 9, which is arranged in parallel to the pin 8.

[0032] The wire 6 leads to the inside of the lamp 2, namely into the gas volume 4 which is surrounded by the lamp body. It extends into the gas volume 4 and is electrically and mechanically connected to a filament 10. The filament 10, on the other hand, is also connected to wire 7 and is thus an element of an electric circuit going from pin 8 to pin 9 through the wires 6, 7 and the filament 10.

[0033] A socket 11, which may be made from ceramic material, encloses the pinch-sealed portion 5. The pins 8 and 9 are firmly held within the socket 11, and the electric connection between wires 6 and 7 and pins 8 and 9 is protected by the surrounding socket 11.

[0034] Furthermore, FIG. 1 shows a temperature sensor 12, which is located inside the socket 11 and is connected, via wires 16 and 17, to pins 8 and 9.

[0035] An electric current which is applied to the pins 8 and 9 will therefore flow from pin 8 through wire 6, filament 10 and wire 7 to pin 9. This is the supply current to drive the lamp 2 in a manner that is known in the art.

[0036] The position of the sensor 12 inside the socket 11 may be chosen according to requirements. In this preferred embodiment, the sensor 12 is located close to the pinch-sealed end 5.

[0037] The temperature sensor 12 is connected in parallel to the filament 10. The wires 16 and 17, which are connected to the sensor 12, are directly contacted with wires 6 and 7 respectively.

[0038] In this embodiment, due to the parallel connection between sensor 12 and filament 10, the temperature measurement and the electric power supply of the lamp operate through the same pins 8 and 9 of the lamp 2. Thus, the temperature measurement can be carried out by reading out the sensor 12 before applying the power to the filament 10, which means that the temperature can be measured directly before the startup of the lamp 2. The measurement can also be carried out during operation of the lamp 2, for example with a digital sensor 12, which can be read out using a digital signal which is modulated onto the drive current which is supplied to the filament 10.

[0039] FIG. 2 shows another end portion 1 of the lamp 2, in which the sensor 12 is wired parallel to the filament 10, like in FIG. 1. The location of sensor 12 is chosen such that the sensor is positioned almost centrally inside the ceramic socket 11.

[0040] FIG. 3 finally shows a lamp 2 in a perspective view. The representation is more realistic than the schematic drawings of FIGS. 1-2. What is shown in FIG. 3 is the socket 12 at the end of lamp 2 with the pins 8, 9.

[0041] The sensor 12 is placed inside a cavity or void 20 which is provided in the socket 11. The sensor 12 is fixed inside the void 20 with a temperature resistant adhesive. If the sensor 12 needs to be protected from outside influences like water etc., the void 20 may be completely filled with resin or cement, so that the sensor 12 is completely sealed in the void 20.

[0042] The socket 11 with its connecting pieces 8, 9 can be taken as a mechanic and electric connecting element, which may be plugged into an appropriate socket for electrically contacting the lamp 2.

[0043] In operation, the temperature sensor 12 can electronically be checked to retrieve a temperature signal before starting the lamp 2. Depending on the result of this measurement, a control system (not shown) can select appropriate voltage and frequency for starting the electric discharge between filament 10 and a second filament (not shown) at the other end of the lamp 2. If the temperature is below a certain threshold value, the electronic control can choose to pre-heat the filament 10 by applying a DC voltage to the pins 8 and 9. Pre-heating the filament 10 will assist the formation of free electrons close to the surface of filament 10 and consequently lead to lower high-voltage being needed for starting the gas discharge.

[0044] In continuous operation, the temperature sensor 12 may from time to time or continuously be read out in order to gather information on the status of the lamp 2. After a certain time of operation, a steady state of temperature will be achieved, which is representative of the status of the lamp. An error condition might be detected, if the temperature of the sensor 12 is outside pre-determined range, which range would be chosen on the basis of the present operating conditions. Such a temperature deviation might indicate an overload, dry-running or failure of the lamp, which would trigger a signal indication the necessity for service.

[0045] Finally, the use of the temperature sensor 12 could be extended to applications in which, before starting the lamp, the temperature values are checked for plausibility. If unexpected deviations between several lamps or a deviation of the temperature of one lamp from a default value are detected, the start-up of the lamp or the entire installation can be prohibited. Such a condition might indicate that the respective lamp 2 with is associated with an unexpected temperature signal is damaged or could otherwise lead to a malfunction. It can specially be avoided to send the high voltage ignition pulse to a lamp with such condition so that potential hazards resulting therefrom can be avoided. This adds to the safety in operation of the whole installation.