EP2248395B1 - Type recognition of a gas discharge lamp to be operated with an electronic ballast - Google Patents

Abstract

The invention relates to a method for determining the type of gas discharge lamp (L) to be operated with an electronic ballast (V). According to said method, the coil voltage and the coil current are measured according to two successive times during the pre-heating phase. The heating power or the heating current is kept constant. From the measured current and voltage values, the cold resistance (Rcold) and the hot resistance (Rhot) are calculated and the differential resistance (Rdiff), that is normally independent of the starting temperature of the coil, is formed therefrom. In order to determine whether the gas discharge lamp is replaced by a substitution resistance (Rsub) for test purposes, it is tested whether the differential resistance (Rdiff) is lower than the substitution resistance (Rsub) and if this is the case, the hot resistance value (Rhot) is set as the differential resistance (Rdiff). With the aid of the thus defined differential resistance (Rdiff), the type of lamp is determined by comparing it to the stored reference values (level 1, level 2, level 3) in order to set corresponding operational parameters.

Description

The invention relates to a method for determining the type of a gas discharge lamp to be operated with an electronic ballast.

Such a method is according to EP 1519638 A1 known. In this known method, the voltage drop across a resistor located on the primary side of the heating transformer is measured at two different times during the preheating phase. The two voltage values thus determined are compared with reference voltage values stored in a memory to determine the lamp type.

After EP 1125477 B1 It is known to determine the filament resistance of the lamp to determine the lamp type by comparison with a reference resistance value stored in a register.

After EP 1103165 B1 the lamp type is identified by measuring the current flowing through the filament. The current is measured during the preheat phase at two consecutive times.

In the not yet published German patent application DE 10 2007 047 142.6 It is proposed to use the measured value of the helical resistance for the determination of the lamp type, but this is a prerequisite is that the power supplied to the heating coil or the supplied filament current are kept constant during the preheating phase. As a result, the following advantageous effect is achieved: During the preheating phase, the coils heat up. With the heating also increases the coil resistance. For example, if the filament of a first type of lamp has the cold resistance R, it may double during the preheating phase, for example 2R. Now, if the filament of a second lamp type has the cold resistance 2R, its hot resistance would be 4R. During the preheating phase, therefore, there is a spreading of the resistance values to the effect that the distance or the difference of the hot resistances is twice as great as that of the cold resistances. Due to the greater distance of the hot resistors a more accurate determination of the lamp type is possible. However, as previously stated, the prerequisite for this is that the power supplied to the filaments or the filament current supplied to the filaments be kept constant during the preheating phase.

Based on the method described above ( EP 1519638 A1 ), the invention has for its object to provide a way to determine the lamp type.

Optionally, "lamp type detection" also means that the number of gas discharge lamps with heating coils supplied in parallel or in series by the operating device can be determined.

The object is achieved by the combination of the features specified in the characterizing part of claim 1.

The solution according to the invention adopts the principle of resistance measurement with heating power held constant during the preheating time or with a constant heating current. In addition to this measure, however, the difference resistance is formed from the measured hot resistance and the measured cold resistance, which in any case is independent of the starting temperature if a helical voltage limiting has not yet been used.

The optional detection of a substitution resistance as a substitute load can trigger a special behavior deviating from normal operation. On the one hand, deviating operating parameters for the subsequent operation can be set for this case, wherein, for example, the preheating time or the sequence behavior of the lamp start can also be changed, but the electronic ballast can also be operated via the detected value of the substitution resistance for later operation, ie after next lamp start, be specified. This can be understood as a kind of programming of the TOE, whereby the respective types of the lamps to be recognized can also be specified. An example of this may be that an ECG has stored the parameter sets for the combination of a 14W and 24W lamp and the combination of a 21W and 39W lamp. Depending on the specification by the Rsub to be connected once, the ECG can later differentiate between a 14W and 24W lamp or a 21W and 39W lamp.

The solution according to the invention allows the reference values for the differential resistances to cover a defined variation range for each lamp type. Thus, a determination of the lamp type is in any case possible if the determined differential resistance falls within one of these ranges of variation. If there is an undefined distance range between two variation ranges and a determined differential resistance falls within this distance range, the lamp type which was last recognized unambiguously can be selected for the determination. Alternatively, however, it is also possible to select the lamp type for the determination whose allocated variation range is adjacent to the distance range and covers differential resistances which are smaller than the determined differential resistance.

Further developments of the method according to the invention are the subject of claims dependent on claim 1.

The invention further relates to a ballast for at least one gas discharge lamp, which is suitable for carrying out the method according to the invention. The features of such a ballast are specified in claim 11.

The dependent of claim 11 claims relate to advantageous developments of this ballast.

According to one embodiment of the invention, the number of parallel and / or serially supplied by the operating device gas discharge lamps of a certain type can be detected. For this purpose, it is checked, for example, whether the validated differential resistance corresponds to n times one of the several corridor ranges. If so, it can be concluded that n lamps of the lamp type are connected in series at the output of the operating device, which is assigned to this corridor area.

It can also be checked whether the validated differential resistance corresponds to 1 / n times one of the several corridor ranges. If so, it can be concluded that n lamps of the lamp type are connected in parallel at the output of the operating device, which is assigned to this corridor area.

Embodiments of the invention will be described below with reference to the drawings.

Fig. 1

ein schematisiertes Blockschaltbild des erfindungsgemäßen Vorschaltgerätes;

Fig. 2

ein Flussdiagramm, welches zeigt, wie das erfindungsgemäße Verfahren praktisch umgesetzt wird;

Fig. 3

eine graphische Darstellung der Abhängigkeit des Wendelwiderstandes von der Vorheizzeit für drei verschiedene Lampentypen sowie sich daraus ergebenden drei Variationsbereiche für den Differenzwiderstand jedes dieser drei Lampentypen;

Show it:

Fig. 1

a schematic block diagram of the ballast according to the invention;

Fig. 2

a flow chart showing how the inventive method is practiced;

Fig. 3

a graph of the dependence of the helical resistance of the preheating time for three different lamp types and the resulting three ranges of variation for the differential resistance of each of these three lamp types;

This in Fig. 1 shown ballast V is used to operate a gas discharge lamp L with two heating coils W1 and W2.

To generate the operating voltage for the lamp L is rectified by a rectifier 1, the mains voltage and smoothed in a smoothing circuit. An inverter 3 generates an alternating voltage which is fed to a series resonant circuit 4. The voltage drop across the capacitor of the series resonant circuit 4 is supplied to the lamp L as the operating voltage.

A programmer 14 connected to a bus determines the start of a preheat phase for the lamp L. He gives to the block 8 a start signal. The block 8 generates the heating power or the filament current for the filaments W1 and W2 of the lamp L. The heating power or the filament current are kept constant during the preheating phase. The heating power or the filament current are led to the lamp L via a block 6, which contains means for limiting the filament voltage. A limitation of the filament voltage is required to avoid a transverse discharge between the individual sections of the heating coils. The filament current flowing through the "cold" filament W2 generates a voltage drop across the resistor R3, which is conducted to the filament current measuring means 7. At a voltage divider R1, R2, a voltage is further removed, which is a measure of the filament voltage at the "cold" coil W2. This is fed to the helical voltage measuring means 9.

The measured values continuously measured by the filament current measuring means 7 and the filament voltage measuring means 9 are supplied to a memory 15. The memory 15 is controlled by the programmer 14 such that the measured values for the filament current and the filament voltage are stored at two successive times during the preheating phase. The stored measured values for the filament current and the filament voltage are fed from the memory 15 from a quotient former 10, which calculates therefrom the cold resistance and the hot resistance of the filament. These values are forwarded by the quotient generator 10 to the difference value generator 11, which calculates the differential resistance therefrom.

The difference value generator 11 supplies the differential resistance to a decision logic 13, which in turn corresponds to a memory 12 by storing a table for reference differential resistances. The decision logic 13 compares the differential resistance calculated in the block 11 with the reference values in the table stored in the memory 12 and determines the type of the lamp L operated by the ballast V. The determined lamp type is reported by the decision logic 13 to the operating parameter setting means 5, which, inter alia, readjust the heating current or the heating power, if the lamp L is of a different type than the previously operated with the ballast V lamp. Further operating parameters may be the preheating time, the ignition voltage, the lamp burning voltage, the lamp current or else parameters for fault shutdowns. However, it is also possible to set operating parameters for the power factor correction circuit, such as, for example, the bus voltage or the dynamics of the control loop.

It should be noted in this regard that the individual blocks in Fig. 1 not necessarily be realized by hardware. Rather, it is also possible that the function of some blocks is realized by a corresponding software in a processor. The block diagram in Fig. 1 should only serve the better understanding.

The logical sequence of the individual method steps for determining the lamp type, ie the software representation of the invention, is described in Fig. 2 shown. This will be explained below.

The representation in Fig. 2 concerns the case that two ballasts are operated in parallel with one ballast. Of course, it also includes the possibility of working with only one lamp.

At the beginning of the preheating phase the cold resistances Rcold1 and Rcold2 are measured by the two lamps. The absolute value of the difference is calculated from the two measured values. Then three cases are distinguished. If the absolute value of the difference is smaller than a first reference value Ref1, it means that the two lamps are of the same type. It then continues in "Case 1".

If the absolute value of the difference is greater than the first reference value Ref1 but smaller than a second reference value Ref2, this means that lamps are ready for operation, but not of the same type. In this case, the path "Case 2" trodden. The result usually results in a lamp being replaced.

Now, the path "Case 1" should be followed, in which the further evaluation is carried out with the lamp whose coil has the lower cold resistance.

It is understood that this point in the flowchart also comes when only one lamp is present. In this case, the splitting of the cold resistances in two paths is eliminated. The further course of the flowchart is limited anyway only to a differential resistance, be it the lamp with the coil with the lower cold resistance or the single lamp.

Furthermore, it is now checked whether the differential resistance Rdiff is smaller than a predefined resistance value. This case is given when the lamp is replaced by a substitution resistor for testing purposes. If this is the case, the cold resistance and the hot resistance do not differ. Therefore, if the decision is "Yes", the differential resistance Rdiff is set equal to the hot resistance Rhot.

In the case of recognizing a substitution resistance value, a special behavior deviating from normal operation can be triggered. For example, deviating operating parameters for the subsequent operation can be set in this case, whereby the preheating time or the sequence behavior of the lamp start are also changed can, the ballast but also operating parameters on the detected value of the substitution resistance for later operation, ie after the next lamp start, be specified. This can be understood as a kind of programming of the ballast, whereby the respective types of the lamps to be detected can be specified. An example of this may be that a ballast has stored the parameter sets for combining a 14W and 24W lamp and the combination of a 21W and 39W lamp. Depending on the specification by the value of the substitution resistance to be connected once, the ballast can later distinguish between a 14W and 24W lamp or a 21W and 39W lamp, thus avoiding the problem that the 14W lamp and the 21W lamp can not be distinguished by their coils.

If the difference resistance Rdiff is greater than the predefined resistance value, i. h., if - because a lamp is inserted - Rcold and Rhot differ sufficiently, then the result of the decision is "no".

Next, the decision is whether the differential resistance Rdiff is smaller than a first stored resistance value "Level 1". If difference resistance Rdiff is less than this level 1, then the decision is made that this is the lamp type 1.

If the difference resistance Rdiff between the already mentioned level 1 and another higher located Level 2, the decision is made that a lamp type 2 is present.

If the difference resistance Rdiff is between the level 2 and another level 3, the decision is made that the lamp type 3 is present.

The terms "Level 1", "Level 2" and "Level 3" will be discussed below Fig. 3 explained in more detail.

If the difference resistance Rdiff falls within the stated limits and the lamp type can thereby be determined, the setting of the lamp parameters is continued according to the determined lamp type.

If, on the other hand, no range has been found in which the differential resistance Rdiff can be classified, then work continues with the last stored value.

Fig. 3 shows the course of the filament resistance in three different lamp types during the preheat phase, which takes 500 ms.

In the first coil, the cold resistance Rcold1 is 2WH, and the hot resistance Rhot1 is 3.88W, where WW stands for a resistance value unit.

In the case of the filament of the second type of lamp, the cold resistance Rcold2 is 4 WW. It rises during the preheat phase to the hot resistor Rhot2 with 14 WW. The filament of the third lamp type starts with the cold resistance Rcold3 at 8 WW. This resistance increases during the preheat phase to the hot resistor Rhot3 with 40 WW.

It can be seen how resistance values spread with thermal heating. The prerequisite is that the coils during the preheating always the same heating power or the same heating current is supplied.

If the difference resistance is now formed in each case from the _hot resistance R _hot and the _cold resistance R _cold , then a differential resistance Rdiff1 of 1.88 W results for the first lamp type. The difference resistance Rdiff2 of the second lamp type is 10 W. The difference resistance Rdiff3 for the third Lamp type is 32 W.

The spreading of the hot resistors Rhot1, Rhot2 and Rhot3 makes it possible to define for the differential resistors Rdiff1, Rdiff2 and Rdiff3 variation ranges which are spaced from each other. The variation ranges are marked with hatching lines.

A secure identification is in any case given if the determined difference resistance of the heating coil of a lamp falls into one of the three hatched areas.

However, it has been found that a satisfactory determination of the lamp type is possible even when working with the three drawn levels. The first level "level 1" is identical to the cold resistance Rcold1 of the first lamp type. Of the second level "level 2" is identical to the hot resistance Rhot2 of the second lamp type. The third level "level 3" lies with a considerable distance above the hot resistance Rhot3 of the lamp type.

With the distance arrows drawn on the right in the illustration, dashed lines show that the ranges of determination for the relevant lamp type extend beyond the lower undefined range to the next level.

The identification zones that go beyond the hatched areas are not compulsory, but have been chosen on a case-by-case basis. It is essential that the hatched areas, ie the variation ranges for the differential resistances, allow identification of the lamp type with great certainty.

In the case of lamp type 3, however, it would be conceivable that - with corresponding prior heating - the cold resistance Rcold3 increases so much in the course of the preheating time of 500 ms that the hot resistance Rhot3 is far above the value (40 WW) which is in Fig. 3 specified. With the assumed constant heating power or the constant helical current, however, this would mean that transverse discharges occur between the individual sections of the helix because the voltage between these sections becomes too high. Here, therefore, the effect of the helical voltage limit sets in connection with block 6 in Fig. 1 was explained. The limitation of the heating voltage causes the hot resistor Rhot3 can not rise to the theoretical value described above, but is limited.

As explained above, according to the invention, the validated differential resistance of the heating coil is compared with predetermined ranges. According to one embodiment of the invention, this approach can also be used to the number of parallel and / or serially supplied by the operating device gas discharge lamps. Even with such a multi-lamp application, it is further possible to deduce the lamp type used (i.e., the associated operating parameters, for example, to be set for preheating, ignition and / or burning operation) as long as a uniform lamp type is used.

For this purpose, it is more precisely checked whether the validated differential resistance corresponds to n times one of the several corridor ranges. If so, it can be concluded that n lamps of the lamp type are connected in series at the output of the operating device, which is assigned to this corridor area.

It is further checked whether the validated differential resistance corresponds to 1 / n times one of the several corridor ranges. If so, it can be concluded that n lamps of the lamp type are connected in parallel at the output of the operating device, which is assigned to this corridor area.

Claims (21)

1. Method for determining the type of a gas discharge lamp (L) to be operated by an electronic ballast (V), having the following steps:

   a) preheating at least one heating filament (W1, W2),

   b) directly or indirectly measuring the filament voltage (U_w) at at least two different times,

   c) determining the lamp type by comparing measured values with stored reference values,

   characterized in that

   d) during the measurement between the two times, the filament current or the heating power supplied to the filament up to a predetermined limit heating power is kept constant,

   e) in addition the heating current is measured,

   f) at the first time the cold resistance (Rcold) and at the second time the hot resistance (Rhot) are calculated from the measured values of the filament voltage and of the filament current,

   g) the differential resistance (Rdiff) is calculated from the hot resistance (Rhot) and the cold resistance (Rcold), wherein, if the differential resistance (Rdiff) is less than a predefined resistance value, the hot resistance value (Rhot) is set for the differential resistance (Rdiff), and

   h) the differential resistance (Rdiff) established according to point g) is used as the measured value to be compared with the stored reference values in order to determine the lamp type.
2. Method according to Claim 1,
   characterized
   in that the reference values for the differential resistances (Rdiff) for each lamp type cover a fixed variation range,
   in that, if the established differential resistance (Rdiff) falls within a variation range, the lamp type associated with this variation range is selected,
   in that, if there is an interval range between two variation ranges and an established differential resistance (Rdiff) falls within this interval range, that lamp type which has been most recently uniquely recognized is selected for the determination, or, as an alternative to this, that lamp type whose associated variation range is adjacent to the interval range and covers differential resistances which are lower than the established differential resistance (Rdiff) is selected for the determination.
3. Method according to Claim 1,
   characterized
   in that step (d) is implemented by regulating the filament current.
4. Method according to one of Claims 1 to 3, characterized by the following step:

   i) adjusting at least one operational parameter for the established lamp type.
5. Method according to one of Claims 1 to 4, characterized
   in that sets of reference values are stored which apply to various preheating values, such as filament current, filament voltage or heating power.
6. Method according to one of Claims 1 to 5, characterized
   in that, if a plurality of lamps (L1, L2) are intended to be operated by the ballast (V), a test is performed to ascertain whether the types of the lamps are identical.
7. Method according to Claim 6,
   characterized
   in that, in order to carry out the test for lamp type identity, the difference in the cold resistances (Rcold) of in each case two lamps (L1, L2) is formed and compared with a first reference value (Rref1),
   and in that non-identity is ascertained if the difference is greater than the first reference value.
8. Method according to one of Claims 1 to 7, characterized
   in that, if a plurality of lamps (L1, L2) are intended to be operated by the ballast (V), a test is performed to ascertain whether, in one lamp, there is a breakage of a heating filament, whose voltage drop is measured for calculating the filament resistance (Rcold, Rhot).
9. Method according to Claim 8,
   characterized
   in that, in order to carry out the test for filament breakage, the difference in the cold resistances (Rcold) of in each case two lamps (L1, L2) is formed and compared with a second reference value (Rref2), and in that a filament breakage is ascertained if the difference is greater than the second reference value.
10. Method according to Claim 9,
    characterized
    in that, if the measurement of the heating currents in the case of a plurality of lamps (L1, L2) operated by the ballast (V) takes place via a common resister (R3), in the event of a diagnosed breakage of a heating filament (W1b, W2b) the calculated filament resistances (Rcold, Rhot) are reduced corresponding to the proportion of the broken heating filament with respect to the total number of heating filaments whose heating current is passed through the measuring resistor (R3).
11. Method for recognizing the number of gas discharge lamps supplied in parallel and/or in series at the output of an operating device with heating filaments, in which the number is implemented with reference to a differential resistance, which reproduces the difference in resistance between a measurement at a first temperature and a comparatively higher temperature.
12. Method according to Claim 11,
    in which a check is performed to ascertain whether the differential resistance corresponds to n times one of a plurality of prescribed corridor ranges, wherein, in the positive case, the conclusion is drawn that n lamps of that lamp type which is associated with this corridor range are connected in series at the output of the operating device.
13. Method according to Claim 11 or 12,
    in which a check is performed to ascertain whether the differential resistance corresponds to 1/n times one of a plurality of prescribed corridor ranges, wherein, in the positive case, the conclusion is drawn that n lamps of that lamp type which is associated with this corridor range are connected in parallel at the output of the operating device.
14. Integrated circuit, in particular ASIC, which is designed for implementing a method according to one of the preceding claims.
15. Ballast (V) for at least one gas discharge lamp (L) with two heating filaments (W1, W2), having:

    - means (8) for generating a constant filament current or a constant heating voltage and for applying the constant heating current or the constant heating power to at least one of the two heating filaments (W1 W2),

    - measurement means (9) for directly or indirectly measuring the voltage drop across the filament (W1 W2),

    - program generator means (14), which fix two different times during the preheating phase at which the voltage drop across the filament (W1, W2) is measured,

    - means (7) for measuring the filament current,

    - storage means (15) for storing the measured values of the voltage drop across the filament (W1, W2) and the filament current flowing through the filament at the two times prescribed by the program generator means (14),

    - means (10) for calculating the filament resistances (Rcold, Rhot) at the two times prescribed by the program generator means (14) by virtue of forming the quotient of the stored values for the measured filament current and the measured voltage drop across the filament (W1, W2),

    - means (11) for calculating a differential resistance (Rdiff) from the filament resistances (Rcold, Rhot), wherein the means (11) for calculating the differential resistance (Rdiff) set the hot resistance value (Rhot) for the differential resistance (Rdiff) if the differential resistance is less than a predefined resistance value,

    - storage means (12) for a table, in which a reference differential resistance value is recorded for each lamp type for a determined filament current intensity or heating power,

    - decision means (12) for determining the lamp type by comparing the calculated differential resistance (Rdiff) with the reference differential resistance values recorded in the storage means (12).
16. Ballast according to Claim 15, further
    characterized by

    - means (5) for adjusting at least one operational parameter for the established lamp type.
17. Ballast according to either of Claims 15 and 16,
    characterized
    in that the means (8) for generating a constant filament current or a constant heating power comprise a controller (8) for the filament current or the heating power.
18. Ballast according to one of Claims 15 to 17,
    characterized
    in that the measurement means (9) for directly or indirectly measuring the voltage drop across the filament (W1, W2) to which the predetermined constant filament current or the predetermined constant heating power is applied comprise a voltage divider (R₁, R₂), which is connected in parallel with the heating filament.
19. Ballast according to one of Claims 15 to 18,
    characterized
    in that, in order to measure the filament current (8), a measuring resistor (R3) is connected in series with the heating filament (W1, W2), and in that the voltage drop across this measuring resistor is used as the measured value for the filament current.
20. Ballast according to Claim 19,
    characterized
    in that, if two or more lamps (L1, L2) are operated by the ballast, the filament current flowing through in each case one heating filament (W1b, W2b) of each of the lamps is passed through the measuring resistor (R3).
21. Ballast according to one of Claims 15 to 20,
    characterized
    in that, in the event of a diagnosed breakage of a heating filament (W1b, W2b), the filament resistance (Rcold, Rhot) calculated by the means (10) is reduced corresponding to the proportion of the broken heating filament with respect to the total number of heating filaments whose heating current is passed through the measuring resistor (R3).

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