WO2001076325A1

WO2001076325A1 - Method and ballast for dimming a light fitted with a fluorescent lamp (l)

Info

Publication number: WO2001076325A1
Application number: PCT/DE2001/001010
Authority: WO
Inventors: Ralf Keggenhoff; Ferdinand Mertens
Original assignee: Trilux-Lenze Gmbh + Co.Kg
Priority date: 2000-03-31
Filing date: 2001-03-16
Publication date: 2001-10-11
Also published as: EP1269801A1; AU2001258187A1; DE10016035A1; DE50101080D1; EP1269801B1

Abstract

The invention relates to a method and a ballast for dimming a light fitted with a fluorescent lamp (L), wherein the ballast automatically detects given lamp types, preferably using a lamp voltage measuring system, and sets operating data to those assigned to the detected lamp type according to an operating data register. A method and a ballast are disclosed for lamp types with a tendency to striation, said ballast additionally supplying a D.C. component (IDC) to the lamp current (IL) for the fluorescent lamp. In lamp types not showing a tendency to striation, a filament circuit (HS) is disclosed, which maintains the temperature of the electrodes at the emission temperature of the emitter material of the electrodes by means of an additional filament current (IH) during a low lamp current (IL) in a very dimmed down state. In a method and a ballast, which are used to operate and dimm all above- mentioned lamp types, the lamp current (IL) is additionally fed a D.C. component (IDC) and the electrode is maintained at the emission temperature of the emitter material of the electrode by a filament connection in the dimmed down state.

Description

Method and ballast for dimming operation of a lamp provided with a fluorescent lamp

The invention relates to a method and a ballast for dimming operation of a luminaire provided with a fluorescent lamp, the ballast automatically recognizing certain lamp types, preferably using a lamp voltage measurement method, and setting those operating data which are assigned to the lamp type currently in the luminaire via operating data register.

From WO 97/24017 an electronic ballast is known with which one or more fluorescent lamps of a lamp type can be operated and dimmed.

In general, depending on the degree of dimming of a fluorescent lamp, two technical problems can arise. A problem is the so-called roll discharge or striation of a fluorescent lamp. This appears when the high-frequency lamp current supplied causes different charge densities in the discharge body of the fluorescent lamp. Successive zones with changing charge density are formed in the discharge body and are visible on the surface of the discharge body in the form of differently colored strips or rings. The light emission from the fluorescent lamp is uneven and can change. This is perceived by users as annoying.

Roll discharge occurs increasingly in many lamp types when the operating data of the supplied high-frequency supply energy deviate from the nominal operating data that are recommended by the lamp manufacturer for the lamp type used. However, it should also be noted that there are categories of lamp types that are unlikely to roll discharge and others that tend to roll discharge at certain operating data even at the recommended rated operating data. Another problem arises when particularly low light radiation and a correspondingly low lamp current have to be set. The lamp current to be set can be so low that the electrode temperature thus reached drops below the emission temperature of the electrode emitter material, at which the electrode can still release sufficient electrons. The fluorescent lamp also emits the light very unevenly in this operating state.

The invention has for its object to provide a method and a ballast with which a plurality of certain automatically recognizable lamp types can be operated and dimmed under optimized conditions.

Several solutions are proposed for the technical problem described. Which solution is preferred depends on which category or categories of lamp types are to be operated and dimmed with the method or the ballast.

In the event that such lamp types are to be operated and dimmed by fluorescent lamps that tend to roll discharge in the nominal operating data recommended by the manufacturer, the task is solved by a method for dimming a lamp provided with a fluorescent lamp with a ballast which has an operating data register and has control electronics with an interface for a dimming signal, certain lamp types, preferably using a lamp voltage measuring method, being automatically recognized and then those operating data are set which are assigned to the recognized lamp type by means of the operating data register, a lamp current being supplied to each electrode of the fluorescent lamp and resulting from an AC component and a DC component, and for each recognizable lamp type a DC component is stored in the operating data register and the control electronics for dimming a fluorescent lamp per Operating data register assigned DC component or for each recognizable The lamp type is either a stepped series of direct current components for different dimming settings or a dimming-dependent direct current characteristic for the direct current component is stored in the operating data register for a dimming range and the control electronics for dimming a fluorescent lamp sets a direct current component that is assigned via operating data register depending on the lamp type and dimming signal. The variable adjustment of the DC component can reliably prevent roll discharge for this category of lamp types. The method is particularly suitable when it is not necessary to be able to set very low light yields and there is no risk that the emission temperature of the electrode emitter material will be undercut due to an excessively low lamp current.

If, on the other hand, lamp types with a low tendency to roll discharge are to be operated and dimmed to a very low light emission, then it is advisable to take a measure with which the electrode temperature can be kept at the emission temperature of the electrode emitter material even with a low lamp current. This is achieved with a method for dimming a luminaire provided with a fluorescent lamp with a ballast which has an operating data register and control electronics with an interface for a dimming signal, certain types of lamps, preferably using a lamp voltage measuring method, being automatically recognized and those operating data then being set which are assigned to the recognized lamp type via the operating data register, with each electrode of the fluorescent lamp being supplied with a heating current and a lamp current, which add up to a total current, and with each recognizable lamp type either a stepped series of heating currents for different dimming positions or for a dimming range a di mation-dependent heating current characteristic curve is stored in the operating data register and the control electronics for dimming a fluorescent lamp sets a heating current that can be controlled by the operating data register depending on the lamp type u nd dimming signal is assigned. If the lamp types to be dimmed are both those that are hardly prone to roll discharge as well as those that tend to have significant roll discharge in the recommended nominal operating data, then the underlying technical problem is solved with a method that is separate from the method according to the claim 1 makes use, with which a proportional direct current supply prevents roll discharge of the fluorescent lamp, and additionally, according to claim 3, a heating current assigned by operating data register is set, which prevents the emission temperature of the electrode emitter material of the fluorescent lamp from falling below when the lamp current is dimmed down. In addition to the method steps of claim 1, the method steps of claim 3 are added, according to which each electrode of the fluorescent lamp is supplied with a heating current which adds up to a total current with the lamp current, with a stepped series of heating currents for each recognizable lamp type either for different dimming positions or for a dimming range, a dimensioning-dependent heating current characteristic is stored in the operating data register and the control electronics for dimming a fluorescent lamp sets a heating current that is assigned via operating data register depending on the lamp type and dimming signal.

In an advantageous development of those methods which provide a heating current setting assigned via the operating data register, when the lamp current changes, the heating current is adjusted by dimming the fluorescent lamp in such a way that the total current remains constant.

The nominal lamp current of the lamp type of the detected fluorescent lamp is advantageously specified as the constant total current, because this means that the load on the lamp comes closest to the recommended nominal operating data and a good compromise between service life and luminous efficacy is to be expected.

The control electronics expediently have a measuring device for the lamp current, a current comparator and a regulating device. bare heating current source, the current comparator forming a current difference between a total current flowing through an electrode of the fluorescent lamp and the measured lamp current, and the current difference being supplied to the heating current source as a control variable for the heating current to be set.

To carry out the method according to claim 1, a ballast for dimming a lamp provided with a fluorescent lamp with an operating data register, control electronics with an interface for a dimming signal, a lamp voltage measuring device with which the lamp types that can be used are automatically recognized, and an adjustable direct current circuit with the DC component of the lamp current is variable, proposed. For example, the voltage range 1 to 10 volts is used for the interface of the dimming signal. The setting of the dimming signal is controlled by an external dimmer.

The adjustable direct current circuit simply has a diode which is followed by a first resistor and a first switch in series in the flow direction and a second resistor and a second switch are connected in series in parallel to these. With this arrangement of resistors and switches, four different levels can be set for the direct current component of the lamp current. For this, the switch positions of the two switches are varied. A first DC level results when both switches are open. A second when switch one is closed and switch two is open. A third when switch one is open and switch two is closed. And a fourth when both switches are closed.

Alternatively, the adjustable DC circuit can have a diode, which is followed by an adjustable current source in the flow direction.

Another alternative is that the adjustable DC circuit has a diode, a field effect transistor and a resistor are connected in series in the flow direction.

In another alternative whose adjustable direct current circuit has a diode, a bipolar transistor and a resistor are connected in series in the flow direction of the diode.

If the lamp types to be dimmed are both those that do not tend to roll discharge as well as those that tend to significantly roll discharge, a ballast is proposed with which a heating current circuit is provided in addition to a DC circuit. The control electronics of the ballast is then provided with a measuring device for the lamp current, a current comparator and a heating current source. The current comparator forms a current difference between the total current flowing through an electrode of the fluorescent lamp and the lamp current measured by the measuring device. This current difference is then fed to the heating current source as a control variable for the heating current to be set.

It is favorable if the measuring device for the lamp current has an induction loop. The induction loop simply wraps around the electrode feeds.

For the sake of simplicity, the current comparator has an operational amplifier, to whose n input the lamp current and to whose p input the total current is applied, the current difference between the total current and the lamp current forming the output signal of the operational amplifier, which is fed to the heating current circuit.

The invention is shown below in a drawing and described in detail with reference to the individual figures. Show it: 1 shows the current distribution in a ballast with a direct current supply for operating lamp types which tend to roll discharge,

2 shows the current distribution in a ballast with a heating current supply for operating lamp types which do not tend to roll discharge,

3 shows the current distribution for a ballast with a direct current supply and a heating current supply for the operation of both lamp types which tend to roll discharge and lamp types which do not tend to roll discharge,

4 shows a high-frequency alternating current, on which a direct current is superimposed,

5 shows a variable DC circuit for adapting the DC component of the lamp current to the lamp type and possibly to the setting of a dimmer,

6 shows an alternative DC circuit,

7 shows an alternative DC circuit,

8 shows an alternative DC circuit,

9 shows a heating current circuit for adapting the heating current,

10 shows an alternative embodiment of a ballast with a heating current supply for operating lamp types which do not tend to roll discharge,

11 the realization of the on-time and off-time of a switch element T as width-modulated pulse signals. In the drawing, the invention is shown schematically using parts of the electronic circuits of a ballast.

FIGS. 1 to 3 show basic current distributions between different embodiments of a ballast and a fluorescent lamp L to be operated.

Figure 1 is part of a ballast for a category of lamp types that tend to roll discharge. To prevent roll discharge, a direct current component I _{DC is} supplied to the lamp current I _L via a _DC circuit GS, with which a roll discharge is reliably prevented. In addition, the fluorescent lamp L is supplied with an AC component I _AC . The total current I _G ~ I _AC ^{+ I} _DC -

Figure 2 is part of a ballast for a category of lamp types that do not tend to roll discharge. A DC circuit is not necessary for these. So that the fluorescent lamps L can be dimmed down to a low light emission, a heating current circuit HS is provided, with which the electrode temperature can be kept at the emission temperature of the electrode emitter material even with a low lamp current I _L , at which sufficient emitter material is still released. The total current I _G = I _H + I _L results.

Fig. 3 is part of a ballast for lamp types which tend to roll discharge and at the same time for those which do not tend to roll discharge. Therefore, both a DC circuit GS and a heating current circuit HS are provided. The DC circuit GS and the heating circuit HS are connected in parallel. The equation I _G = I _H + I _L and the equation I _G = I _AC + I _DC + I _H apply.

4 is a coordinate system in which the time profile of a high-frequency alternating current I _AD and a direct current partly I _{DC are} entered. The alternating current I _AD is the superposition of the pure alternating current component I _AC (not entered here) and the direct current component I _DC .

4, the function of the alternative direct current circuits, which are shown in FIGS. 5 to 8, can be understood. Each of the direct current circuits of FIGS. 5 to 8 has an impedance P connected in parallel with the fluorescent lamp L. The latter each has a diode D and an adjusting device V connected downstream of the diode D, with which the direct current component I _DC can be adjusted in steps or continuously.

During a negative half-wave of the alternating current I _AC, it flows exclusively through the fluorescent lamp L, because the diode D blocks the parallel-connected impedance P in this current direction. During a positive half-wave, part of the alternating current I _{AC is} branched off via the impedance P. The proportion of the direct current component I _DC branched off via the impedance P depends on the setting of the adjusting device V.

5 is a DC circuit GS, whose adjusting device V has two branches ZI and Z2 connected in parallel, a resistor R1 and a switch S1 being connected downstream in the flow direction of the diode D in the branch ZI and a resistor R2 in the branch Z2 with a resistance value different from the resistance R1 and a switch S2 are connected downstream. With this construction, four different levels can be set for the direct current component I _{DC of} the lamp current I _L. For this purpose, the switch positions of the two switches S1 and S2 are varied. A first DC level results when both switches S1 and S2 are open. A second when switch S1 is closed and switch S2 is open. A third when switch S1 is open and switch S2 is closed. And a fourth when both switches S1 and S2 are closed.

The DC circuit GS shown in FIG. 6 differs of Fig. 5 only by the adjusting device V. In this, the diode D is followed by an adjustable current source S, via which the direct current component I _DC can be set continuously.

The adjusting device V of the direct current circuit GS according to FIG. 7 alternatively has a field effect transistor Q which, via a control voltage U _E applied to it, adjusts the direct current component I _{DC of} the lamp current I _L. In addition, the field effect transistor Q is followed by a resistor R in series.

A further alternative is the adjusting device of the DC circuit GS according to FIG. 8, in which a bipolar transistor B is used, which likewise effects an adjustment of the DC component I _{DC of} the lamp current I _L via a control voltage U _E applied to it. In addition, the bipolar transistor B has a resistor R connected in series.

Finally, FIG. 9 shows an embodiment of a heating current circuit HS which forms part of the control electronics of the ballast. This has a measuring device M for the lamp current I _L. The measuring device M is provided with an induction loop IS which wraps around the electrode feeds. In addition, the control electronics have a current comparator K and a controllable heating current source HT. A current difference is formed with the current comparator K between the total current I _G flowing through the electrode E1 of the fluorescent lamp L and the lamp current I _L measured by the measuring device M. This current difference is then fed to the heating current source HT as a control variable for the heating current I _H to be set. The current comparator K has an operational amplifier OP, to the n input of which the lamp current _L and to the p input of which the total current I _{G is} applied, the current difference between the total current I _G and the lamp current I _L forming the output signal A of the operational amplifier OP , which is supplied to the heating current source HT as a controlled variable. FIG. 10 shows a section of an alternative construction of a ballast with a direct current supply and a heating current supply for operating both lamp types which tend to roll discharge and lamp types which do not tend to roll discharge. A common control circuit ST is provided for the heating and direct current control, with which periodic opening and closing of an electronic switch element T, for example a field effect transistor, is controlled. The switch element T is connected in parallel to the fluorescent lamp L and connected to a feed of the two electrodes of the fluorescent lamp L.

On the one hand, the amplitude and / or the frequency of an inverter (not shown) of the ballast are varied with the control circuit ST for dimming the fluorescent lamp L. On the other hand, the heating current is set by periodically switching the switch element T on and off at a frequency which corresponds to or is greater than twice the frequency of the inverter.

FIG. 11 shows how the on-time and the off-time of the switch element T are implemented as width-modulated pulse signals with the control circuit ST. The switch-off duration of the switch element T during a positive half-wave and the switch-off duration of the switch element T during a negative half-wave of the current supplied by the inverter preferably have the same pulse widths t _λ and t ₃ . In this way, the electrodes are heated uniformly during a positive half-wave and a negative half-wave of the inverter current.

However, the pulse width t ₂ for the switched-on state of the switch element T during a positive half-wave preferably differs from the pulse width t ₄ for the switched-on state during a negative half-wave of the inverter current. The size and the sign of the DC component are controlled via the pulse widths t ₂ and t ₄ . If the Pulse width t _{2 is} less than the pulse width t ₄ , the DC component shifts the inverter current into the negative. If the pulse width t _{4 is} smaller than the pulse width t ₂ , the DC component shifts the inverter current into positive.

For the list of characters

A output signal

B bipolar transistor

C capacitor

D diode

El electrode

GS DC circuit

HS heating current circuit

HT heating power source

- ' ^• AC AC component

- "- AD superimposed alternating current

-I-DC DC component

IG total flow H heating current

II lamp current

IS induction loop

K current comparator

L fluorescent lamp

M measuring device

OP operational amplifier

P impedance

Q field defect transistor

R resistance

Rl resistance

R2 resistance

S power source

Sl switch

S2 switch

ST control circuit

T switch element tl pulse width t ₂ pulse width ₃ pulse width 14 t ₄ pulse width

U _E control voltage

V Adjustment device

ZI branch

Z2 branch

Claims

15Procedure and ballast for dimming operation of a luminaire provided with a fluorescent lamp

1. Method for dimming a luminaire provided with a fluorescent lamp (L) with a ballast which has an operating data register and control electronics with an interface for a dimming signal, certain types of lamps, preferably using a lamp voltage measuring method, being automatically recognized and those operating data then being set, which are assigned to the recognized lamp type via the operating data register, with each electrode of the fluorescent lamp ( _L ) being supplied with a lamp current ( _IL ) which is composed of an AC component (I _AC ) and a DC component (I _DC ), and for each recognizable lamp type one DC component (l _DC ) is stored in the operating data register and the control electronics for dimming a fluorescent lamp (L) sets the direct current component (I _DC ) assigned via the operating data register or for each recognizable lamp type either a stepped row v for different dimming positions on direct current components (I _DC ) or for a dimming range a dimming-dependent direct current characteristic curve for the direct current component (I _DC ) is stored in the operating data register and the control electronics for dimming a fluorescent lamp (L) sets a direct current component (I _DC ), which is set via operating data register depending on the lamp type and dimming signal is assigned.

2. Method for dimming a luminaire provided with a fluorescent lamp (L) with a ballast which has an operating data register and control electronics with an interface for a dimming signal, certain types of lamps, preferably using a lamp voltage measuring method, being automatically recognized and thereafter the 16 operating data can be set, which are assigned to the recognized lamp type via operating data register, with each electrode (El) of the fluorescent lamp (L) being supplied with a heating current (I _H ) and a lamp current (I _L ), which result in a total current (I _G ) add up, and with each recognizable lamp type either a stepped series of heating currents (I _H ) for different dimming positions or a dimming-dependent heating current characteristic for a dimming range is stored in the operating data register and the control electronics for dimming a fluorescent lamp (L) have a heating current (I _H ) that is assigned via the operating data register depending on the lamp type and dimming signal.

3. The method according to claim 1, characterized in that a heating current (I _H ) is fed to each electrode of the fluorescent lamp (L), which adds up with the lamp current (I _L ) to form a total current (I _G ), with either recognizable lamp type either for different dimming settings, a stepped series of heating currents (I _H ) or for a dimming range a dimming-dependent heating current characteristic is stored in the operating data register and the control electronics for dimming a fluorescent lamp (L) sets a heating current (I _H ), which is set via operating data register depending on the lamp type and Dimming signal is assigned.

4. The method according to any one of claims 1 to 3, characterized in that when the lamp current (I _L ) is changed by dimming the fluorescent lamp (L), the heating current (I _H ) is adapted such that the total current (I _G ) remains constant.

5. The method according to claim 4, characterized in that the nominal lamp current of the detected fluorescent lamp (L) is specified as a constant total current (I _G ). 17

6. The method according to any one of claims 2 to 5, characterized in that the control electronics comprise a measurement device (M) for the lamp current (I _L), a current comparator (K) and a variable heating-current source (HT), wherein the current comparator (K) a Forms the current difference between a total current (I _G ) flowing through an electrode (El) of the fluorescent lamp (L) and the measured lamp current (I _L ) and the current difference is supplied to the heating current source (HT) as a control variable for the heating current (I _H ) to be set.

7. Ballast for dimming a lamp provided with a fluorescent lamp (L) with an operating data register, control electronics with an interface for a dimming signal, a lamp voltage measuring device with which the lamp types that can be used are automatically recognized, and an adjustable DC circuit (GS) with a DC component (I _DC ) of the lamp current (I _L ) is changeable.

8. Ballast according to claim 7, characterized in that the adjustable direct current circuit (GS) has a diode (D), which is connected in series in the flow direction, a first resistor (Rl) and a first switch (Sl) and parallel to these a second resistor ( R2) and a second switch (S2) are connected in series.

9. ballast according to claim 7, d a d u r c h g e k e n n z e i c h n e t that the adjustable DC circuit (GS) has a diode (D) which is connected in the flow direction an adjustable current source (S).

10. Ballast according to claim 7, characterized in that the adjustable DC circuit (GS) has a diode (D) which has a field-effect transistor (Q) in series in the flow direction 18 a resistor (R) are connected downstream.

11. Ballast according to claim 7, so that the adjustable direct current circuit (GS) has a diode (D) which is connected in series in the flow direction to a bipolar transistor (B) and a resistor (R).

12. Ballast according to one of claims 7 to 11, characterized in that the control electronics with a measuring device (M) for the lamp current (l _L ), a current comparator (K) and a heating current circuit (HS) is provided.

13. ballast according to claim 12, characterized in that the measuring device (M) for the lamp current (I _L) has a Induktionsmeßschleife (IS).

14. Ballast according to claim 12 or 13, characterized in that the current comparator (K) has an operational amplifier (OP), at the n input of the lamp current (I _L ) and at the p input of the total current (l _G ) is applied, the current difference between total current (I _G ) and lamp current (I _L ) forms an output signal (A) which is fed to the heating current circuit (HS).