Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
  • H05B41/14—Circuit arrangements
  • H05B41/36—Controlling
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
  • H05B41/14—Circuit arrangements
  • H05B41/36—Controlling
  • H05B41/38—Controlling the intensity of light
  • H05B41/39—Controlling the intensity of light continuously
  • H05B41/392—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor
  • H05B41/3921—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations

Definitions

• the present invention relates to the operation of AC powered fluorescent lamps, such as gas discharge lamps. More specifically, the invention relates to controls for such lamps, which take into account the directly or indirectly determined lamp temperature in the lamp control. Typically, such regulations are used in control gear such as electronic ballasts.
• fluorescent lamps operated with dimmable electronic ballasts can be operated close to the nominal mode - and thus at nominal power - and on the other hand with dimmed, ie reduced lamp power.
• the operation with nominal power is relatively unproblematic compared to the operation with reduced, in particular greatly reduced lamp power.
• the permissible lamp ambient temperatures in dimming operation are specified much narrower compared to the normal power operation. Namely, at low dimming values, the ambient temperature of the lamp plays a greater role for a stable regulation of the dimmed fluorescent lamps, ie a regulation with constant light output and in particular a regulation which reliably prevents unwanted extinction of the lamp.
• the increased lamp ambient temperature dependency at low dimming levels is caused, inter alia, by the fact that the lamp voltage at high ambient temperatures and small lamp currents (as they occur with dimmed lamp power) increases sharply and may assume unacceptably high values.
• the temperature in the immediate vicinity of the lamp is crucial, which does not necessarily have to be the ambient temperature of a possibly spatially and thermally separately provided electronic ballast.
• the temperature of the electronic ballast can not be used directly to assess the lamp ambient temperature.
• EP 838 132 A1 teaches in this context that the voltage applied to the lamp should be used as an indicator of the lamp temperature. When the lamp voltage rises sharply, a critical state is concluded and the lamp is switched off, if necessary.
• the use of the total lamp voltage as an indicator of such critical conditions of lamp operation is problematic in that the lamp voltage is not clear for detecting this condition. Rather, the non-linearity of a fluorescent lamp can also lead to high lamp voltages in non-critical states that do not require further intervention require the control device. For the rest, the EP sees
• the invention has accordingly set itself the task of providing an improved technique for detecting the ambient lamp temperature.
• the central idea of the invention is to apply a targeted DC voltage to the lamp voltage.
• the above-mentioned critical states can then be detected by detecting and evaluating the lamp voltage.
• the targeted admission of the DC component thus enables a more accurate compared to the prior art detection of the lamp temperature.
• a method of determining the temperature of an AC lamp powered fluorescent lamp In this case, the AC voltage is deliberately superimposed on a DC voltage.
• the lamp voltage of the fluorescent lamp is detected, evaluated as a parameter for the temperature of the fluorescent lamp and used as the input variable of the lamp control.
• the DC voltage component of the lamp voltage can be evaluated. Additional parameters of the lamp voltage can optionally also be taken into account during the evaluation.
• the lamp voltage can be evaluated, for example, based on an asymmetry of the periodically extending lamp voltage.
• the evaluation of the lamp voltage can be determined, for example, based on the distances of successive zero crossings of the lamp voltage.
• the impedance can be evaluated digitally, in particular if the total lamp power control is digital.
• the evaluation of the lamp voltage can be determined, for example, by digital counting of the distances between successive half-waves (zero crossings) of the lamp voltage.
• the power of the lamp can be specifically controlled to a power lying above this predetermined dimming value (set value), especially at low dimming values.
• This increase in the lamp power over a predetermined dimming value or setpoint can thus be carried out in particular at low lamp powers, in which u.a. There is a risk of the lamp extinguishing at low ambient temperatures.
• Such a method can be used in an electronic ballast.
• the present invention also relates to an electronic ballast for Fluorescent lamps that use a digital circuit for
• the present invention also relates to a circuit for determining the temperature of a fluorescent lamp operated with alternating voltage.
• a detection circuit for the voltage of the fluorescent lamp is provided, the output signal of which can be supplied to an evaluation circuit, which evaluates the detected lamp voltage as a parameter for the temperature of the fluorescent lamp and considered, for example, in the course of a digital lamp control.
• the means for the targeted superposition of a DC voltage to the fluorescent lamp may have a DC voltage path, which is provided parallel to the AC operating voltage for the lamp.
• the present invention also relates to an electronic ballast having such a circuit.
• the invention also relates to a luminaire which has such an electronic ballast.
• 1a shows a schematic representation of relevant components of an electronic ballast
• 1b and 1c are simplified circuit diagrams for explaining the background of the present invention
• FIGS. 2 and 3 are illustrative of the indirect digital detection of the impedance of the lamp, which may then be used as a lamp temperature parameter;
• Fig. 5 shows the dependence of the impedance on the lamp current for different lamp temperatures
• Fig. 6 shows the application of the invention to multi-lamp lights.
• Impedance of the discharge path of the lamp at the respective operating point both a dependence on the discharge current
• I DIS Vorr ⁇ ballast is kept substantially constant, thus there is a dependence of the lamp impedance Z D i S of the ambient temperature T.
• the present invention now proposes to selectively store a DC voltage V DC from a high-impedance source for the high-frequency operating voltage for the lamp U HF , such that the voltage applied to the lamp is then different with respect to different criteria, such as the DC component, it can be evaluated under which conditions the lamp is currently operated:
• the source voltage V DC of the DC source is divided according to the resistance ratio of the internal resistance of the DC source Zi to the impedance of the lamp Zi at the current operating point, wherein the lamp resistance Z 1 depends inter alia on the ambient temperature of the lamp T. This can also be done via the resistance ratio
• the electronic ballast can take appropriate countermeasures to meet. It makes sense, the DC share of
• Lamp voltage V DC , Z L detected over a certain time range and then averaged to account for temporal compensation operations in the lamp.
• the ballast for example. Automatically increase the lamp power, and indeed until the DC component of the lamp voltage V DC , ZL back to allowable Values, ie has fallen below the predetermined threshold.
• the electronic ballast also increases the lamp power beyond possibly supplied externally set values (dimming commands, etc.) and thus the stability of the lamp control a higher priority than the strict compliance specified outside values (dimming commands, etc.) is granted.
• This increase in the lamp power can be limited according to the invention to the range of low dimming values.
• the electronic ballast decreases the lamp power back again until either the default again
• Threshold for the DC component of the lamp voltage V DC , ZL is reached, or now the predetermined target value (dimming command, etc.) for the lamp power has been reached correctly.
• Fig. Ia an electronic ballast according to the invention is shown schematically, for example.
• An inverter with two switches Sl, S2 converts a provided DC voltage (DC link voltage, bus voltage) into a high-frequency operating voltage for a resonant load circuit.
• the alternating voltage is tapped at the midpoint of the two switches Sl, S2.
• the resonant load circuit has an inductance L R , a capacitor C R and a coupling capacitor C ⁇ .
• a lamp which is indicated schematically by means of its internal resistance R D i s , is operated as generally known, with this high-frequency AC voltage.
• the control of the switches Sl, S2 and in particular the switching frequency of the alternating switching of the two switches Sl, S2 is carried out by a lamp control, which can be performed digitally according to the invention.
• the described alternating operating voltage for the lamp is deliberately superposed on a DC voltage component V DC .
• a diode D and a resistor R DC are provided parallel to the inductance L R and the coupling capacitor C ⁇ , which represent a DC voltage path parallel to the resonant circuit for the AC voltage.
• Parallel to the lamp is a voltage divider with two
• Resistors Rl, R2 provided. A signal that the
• Lamp voltage V ZL reproduces is at the midpoint of the
• the lamp control circuit further operating parameters such as the lamp current, etc., and externally predetermined setpoints (Dimmbetatione, etc.) are supplied.
• FIG. 6 A development of the present invention is shown in Figure 6 and relates to the application to multi-lamp electronic ballasts, in which therefore several individual lamps are operated in parallel.
• multi-lamp luminaires often the problem arises that the balancing of the lamp performance is often not guaranteed, especially at low dimming and low temperatures.
• this also means that, for the reasons stated above, the lamp voltages of the two lamps operated by the same electronic ballast can have greatly different values.
• Lamp power may be increased beyond a specified setpoint. This increase in the application of the invention to multi-flame control gear now not (only) the goal to avoid extinction of one of the two lamps, but primarily, at low ambient temperatures of the two lamps beyond a certain threshold asymmetry of the light output of the two lamps reduce.
• the lamp power control can be carried out digitally.
• FIG. 2 shows a circuit implementation of this exemplary embodiment with an up / down counter 107 which receives a signal U ZER0 as the actual input signal and, furthermore, as control signals a high-frequency reference clock signal CLK and a reset or reset signal.
• the advantage here is the digital detection of the feedback signal by evaluation, for example, the zero crossings of the lamp voltage.
• the signal U ZERO assumes during each positive half wave of the voltage applied to the terminal V L lamp voltage to a positive and otherwise a negative voltage level and thus detects the zero crossing of the lamp voltage.
• the counter 107 is started at zero crossing of the lamp voltage and counts during the following half wave of
• Lamp voltage either up or down.
• the zero crossings are digitally counted.
• the counting direction of the counter 107 is reversed.
• the current count N of the counter 103 is a comparator connected, which may be formed for example by the comparator 103 already described above. This comparator 103 compares the current counter reading N with the initialization value or the original counter reading of the counter 107. If there is no rectification effect, the counter reading N must have reached the output value N 0 again after reaching the next zero crossing of the lamp voltage. On the other hand, if the count N deviates from the output value N 0 , a DC voltage component is present in the lamp voltage.
• the comparator 103 compares the count N with the output value No within certain tolerance limits, so as not to prematurely infer the presence of a rectifying effect.
• the output signal of the comparator 103 is supplied via a clocked by a latch signal D flip-flop 108 of the Meßphasen Kunststoffung 900, which - as described above - evaluates this signal and in particular performs an event filtered score, ie only on the presence of a DC voltage component closes, if one of the comparator 103, for example, 32 times successively every 255th Period of the lamp voltage, a DC component is reported.

Landscapes

• Circuit Arrangements For Discharge Lamps (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Related Child Applications (1)

Publications (1)

Family

ID=36947591

Family Applications (1)

Country Status (4)

Cited By (1)

Families Citing this family (1)

Citations (4)

Family Cites Families (2)

• 2005
  • 2005-04-22 DE DE200510018763 patent/DE102005018763A1/de not_active Withdrawn
• 2006
  • 2006-04-04 EP EP06724015.0A patent/EP1872635B1/de not_active Not-in-force
  • 2006-04-04 WO PCT/EP2006/003060 patent/WO2006111269A1/de not_active Application Discontinuation
  • 2006-04-04 CN CN2006800134546A patent/CN101164390B/zh not_active Expired - Fee Related

Patent Citations (4)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events