Electric lamp and discharge devices: systems – With automatic shunt and/or cutout
Patent
1996-09-25
1998-01-06
Pascal, Robert
Electric lamp and discharge devices: systems
With automatic shunt and/or cutout
315224, 315209R, 315307, 315360, 315DIG7, H05B 3700
Patent
active
057058946
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method and apparatus for operating at least one fluorescent lamp using an electronic ballast.
It is known to operate fluorescent lamps by means of electronic ballasts at high frequency in the context of a limited lamp current with a predetermined constant power and increased economy compared with other conventional circuit arrangements used for lamp operation. Therefore, fully electronic ballasts have already become accepted to a large extent and are known in a multiplicity of individual solutions. For example, reference is made in this connection to the articles in the journal 148 to 154 with further literature references.
Fully electronic ballasts are universal devices which can be used advantageously for conventional AC mains voltages in a relatively broad tolerance range, a broad range of permissible mains frequencies and, finally, are even suitable for DC voltage supply. However, an essential problem in the case of electronic ballasts is based on the fact that lamp tolerances have to be taken into account and a variety of disturbances of lamp operation on account of a variety of causes can occur and must be reliably detected. Thus, for example, a fluorescent lamp which has become untight behaves completely differently in operation compared with an aged fluorescent lamp having an increased filament resistance on account of the aging process, and, in turn, a distinction can be made between these cases and disturbances on account of the occurrence of a broken filament. In all these cases, the disturbance must be identified unambiguously as a fault which is endangering the electronic ballast, if appropriate even the load circuit with the defective fluorescent lamp, too, and the driving of the defective fluorescent lamp must be deactivated. However, disturbances occurring briefly in the supply network, too, can additionally influence the lamp operation; in this case the lamp current must be limited to permissible values, on the other hand brief disturbances of this type should not lead to the disconnection of the lamp. Finally, it is desired for maintenance reasons and also already known to put the electronic ballast into a reset standby state when a lamp fault has occurred, from which standby state an automatic restart of the exchanged lamp can take place after a lamp change, i.e. for eliminating the fault.
For the reasons outlined and on account of the fact that in some instances considerable voltage spikes occur at least in the actual load circuit, thoroughly narrow limits are imposed on the configuration of fully electronic ballasts in terms of circuitry. It is therefore customary to construct electronic ballasts at least predominantly using analog circuit technology, which in many cases stands in the way of integration for an electronic ballast. Commercially available electronic ballasts are therefore relatively extensive circuits having a multiplicity of discrete components, and the production and testing are correspondingly complicated and expensive.
SUMMARY OF THE INVENTION
It is therefore a purpose of the present invention, on the basis of an analysis of the operations proceeding during starting of the lamp and on the basis of the monitoring functions resulting from various causes of disturbances, to provide a basis for a functional principle which allows the electronic ballast to be implemented using integrated circuit technology to a significantly higher degree than was customary hitherto.
Therefore, the present invention is based on the object of providing a method of the type mentioned in the introduction which permits, during normal lamp operation, simple and reliable control of the power converted in the load circuit, containing at least one fluorescent lamp, with the fluorescent lamp to a constant value, and which allows at the same time, by means of superordinate monitoring of the functioning of the lamp, an unambiguous evaluation of all the states in unstable regions, that is to say during starting of the lamp, but also in the eve
REFERENCES:
patent: 4616158 (1986-10-01), Krummel et al.
patent: 5049790 (1991-09-01), Herfurth et al.
patent: 5424613 (1995-06-01), Moriarty, Jr.
patent: 5583399 (1996-12-01), Rudolph
Vorschaltgeraete, Peter Heinrich, pp. 45-48. Peter Heinrich, pp. 148-154.
Pascal Robert
Philogene Haissa
Siemens Aktiengesellschaft
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