EP2232953B1 - Method and device for detecting a static index of a lighting device - Google Patents

Abstract

A method for detecting a statistical characteristic of a lighting device is provided. The method may include a) generate a random number within a prescribable value range; b) compare the random number with a comparison number; c) c1) if the comparison of step b) yields a match: increase the count of a storage device by one step width.

Description

Technical area

The present invention relates to a method and apparatus for acquiring a statistical index of a lighting device.

State of the art

The present invention generally relates to the detection of statistical characteristics of a lighting device. These include, for example, operating hours or switch-on operations of the lighting device. The cause of this measure is that, for example, the luminous efficacy of LEDs is highly age-dependent. Depending on the recorded operating hours can then be changed as a countermeasure, for example, the control of the LEDs. For defective returns, the number of operating hours or the number of switch-on processes is an important criterion in determining the cause of failure. In critical application areas of lighting devices, such as surgical lights, traffic lights, street lights, maintenance intervals can be adhered to after recording the operating hours or the switch-on and thus far-reaching failures of the lighting device can be almost completely prevented.

US2002 / 00113560 discloses a lighting device wherein the operating time is measured.

In order to acquire such statistical key figures, different memory devices are used in the prior art, for example flash memory, E2Proms, Harddisks, etc. Flash memory is the cheapest option, but has the disadvantage that they are not as often writable as the other storage media. Typically, flash memories can be written up to about 50,000 times. E2Proms, which are significantly more expensive than flash memory, have the advantage of allowing up to 500,000 write cycles. On the one hand, hard disks as storage medium require that they have to be run up to perform a write operation, which is associated with time and energy requirements, and on the other hand, they are expensive even in small versions.

The shorter the time unit that is to be acquired, for example hours or seconds, the more often write cycles must be performed and the greater the requirements for the selected storage medium. Moreover, there is the problem that when switching off the lighting device, the internal supply must remain sufficiently long, so that the index can be secured. This is accompanied by the further disadvantage that large and therefore expensive buffer capacitors must be made available for the supply of the relevant components for the storage process.

Presentation of the invention

The object of the present invention is therefore to provide a method and a device for acquiring a statistical index of a lighting device that makes the use of more cost-effective Storage media, in particular the use of flash memory allows.

This object is achieved by a method having the features of patent claim 1 and by a device having the features of patent claim 7.

The present invention is based on the finding that the required accuracy for such statistical characteristics of lighting devices is usually not particularly high. In general, a value on single percent is exactly sufficient. Therefore, it is possible not to do every write cycle, but to store only every tenth, hundredth or every thousandth cycle. The invention is further based on the recognition that this can be accomplished without counting if a random variable is used to determine whether or not a write cycle is performed this time. This reduces the number of write cycles, with the result only scaled by a certain factor at the end. This strategy also makes it possible to perform the write cycles even during the operation of the lighting device, so that it does not rely on buffering the power supply for the devices active in the write operation.

In the prior art, if a plurality of recordable cells are provided in a memory device, so that from one to the next cell is transferred to prevent a failure after a prescribable number of write cycles, the memories can be made smaller or wider in the present invention Operating data are recorded, for example, cycle type, temperature integral, etc.

A particular advantage of the present invention is that, despite a low number of write cycles, it enables detection even of very short operating times, for example 1 s or 10 s.

In the method according to the invention, therefore, a random number is first generated within a predefinable value range and then the random number is compared with a comparison number. If this comparison results in a match, the count of a storage device is increased by one increment.

The comparison number is preferably a predefinable number from the range of values from which the random number is generated.

In addition, if the comparison step does not result in a match, it is preferably provided to terminate the method by one increment without increasing the count of the memory device.

In the aforementioned preferred embodiments, the characteristic number is preferably correlated with the switching-on operations of the lighting device, wherein the said steps are run through each time the lighting device is switched on.

In another category of preferred embodiments, the comparison number may be correlated with the count of a timing device that is started upon turning on the lighting device. In this case, the method according to claim 1 preferably further comprises the following steps: If the comparison step If there is no match, the comparison step, in which the comparison number continuously changes due to the time detected by the time measurement device, is repeated until a match is achieved, in which case the count of the memory device is increased by one increment. However, if the lighting device is turned off before achieving a match, the process is ended.

In this case, it is particularly preferred if after increasing the count of the memory device by one step and as long as the lighting device is not switched off, wait until the count of the time measuring device has reached the value corresponding to the maximum value of the predefinable value range in the step of generating corresponds to a random number, and then continues with this generating step.

Preferably, the counter reading of the memory device is continued after each switching off of the lighting device, so that the statistical characteristic number of the lighting device can be detected over many switch-off processes. Preferably, the increment by which the count of the memory device is increased, 1.

A device according to the invention for acquiring a statistical characteristic number of a lighting device comprises a device for generating a random number within a predefinable value range, a comparison device for comparing the random number with a comparison number and a memory device such is coupled to the comparison device such that if the comparison of the random number with the comparison number results in a match, the count of the memory device is increased by one increment.

The preferred embodiments presented in connection with the method according to the invention and their advantages apply correspondingly, as far as applicable, to the device according to the invention. It is provided that corresponding devices are provided for each of the steps of the preferred embodiments of the method according to the invention.

Brief description of the drawings

Fig. 1

in schematischer Darstellung ein Flussdiagramm für ein erstes Ausführungsbeispiel eines erfindungsgemäßen Verfahrens;

Fig. 2

in schematischer Darstellung ein Flussdiagramm für ein zweites Ausführungsbeispiel eines erfindungsgemäßen Verfahrens;

Fig. 3

für das Ausführungsbeispiel von Fig. 2 einen Ausschnitt im Zeitbereich;

Fig. 4

für das Ausführungsbeispiel von Fig. 2 das Ergebnis einer Computersimulation; und

Fig. 5

in schematischer Darstellung ein Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. Show it:

Fig. 1

a schematic diagram of a flowchart for a first embodiment of a method according to the invention;

Fig. 2

a schematic diagram of a flowchart for a second embodiment of a method according to the invention;

Fig. 3

for the embodiment of Fig. 2 a section in the time domain;

Fig. 4

for the embodiment of Fig. 2 the result of a computer simulation; and

Fig. 5

a schematic representation of an embodiment of a device according to the invention.

Preferred embodiment of the invention

Fig. 1 shows a schematic representation of a flowchart for a first embodiment of a method according to the invention. This applies, for example, to the case that the number of switch-on operations of a lighting device is to be recorded as a key figure. It begins in step 100 with the turning on of the lighting device. In step 120, a random number between 0 and a predefinable maximum value of a value range, in the present case 255 (corresponding to 2 ⁸ - 1), is generated. If the comparison of the random number generated in step 120 with an arbitrary comparison number from the same value range yields a match, then in step 160 the value of a memory cell of a memory device is increased by 1. Subsequently, the process is terminated in step 180, irrespective of when the lighting device is turned off. If the comparison does not result in a match in step 140, the method is also ended in step 180 without increasing the value in the memory cell.

Fig. 2 shows a schematic representation of a flowchart for a second embodiment of a method according to the invention. This embodiment is used to detect the operating time of a lighting device, and is used in particular for the realization of an operating seconds counter. It begins with the turning on of the lighting device in step 200. In step 220, a random number is generated in a range between 0 and in the present case 65535 (corresponds to 2 ¹⁶ - 1). The maximum value of the value range can be set arbitrarily, but determines the actual number of executed Write cycles. The larger this maximum value is selected, the smaller the number of actual write cycles to be performed, as will be explained in more detail below. In step 240, a second counter of a timer is started. In the comparison made in step 260, the random number is compared with the current value of the second counter until it matches. If this is the case, in step 280 the value in a memory cell of a memory device is increased by 1. Subsequently, it is waited in step 300 until the second counter has reached the maximum value of the predetermined value range, in this case 65535. Then, it returns to step 220, repeating steps 220 to 300 until the lighting device is turned off. After switching off the lighting device, the method is started from the beginning, in particular regardless of how far in step 300 has already been counted. This includes that when the method is run through for the first time, the method is terminated already before a "yes" in step 260 or before reaching the value "65536" in step 300.

Fig. 3 shows the time course of the method according to the embodiment of Fig. 2 , In this case, blocks of a length of 65535 s each strung together. In each block Bi a random number is schematically drawn. Moreover, switch-off _times t _ausi are continuously entered. In block B1, the switch-off time t _{out1 is} after the time specified by the random number, so that the count in the memory cell increases to 1. In block B2, the switch-off time t out _{2 is the} same as in block B3, the switch-off time t _off3 after the time, which is in each case predetermined by the random number generated in the respective step 220. This leads in each case to a further increase of the meter reading. In block B4, the lighting device is not switched off at all, but the switch-off time _{t4 is} already in block B5. This leads to the increase of the count to the value 4 at the time, which is determined by the random number generated for the block B4. In the block B5, the timing determined by the random number is ₄ after the turn-off timing t, so that the count is not increased. In block B6, the switch-off time t _{out5 is} before the time determined by the random number, so that the count remains unchanged.

Fig. 4 shows a schematic representation of the count of the storage device for an assumed operating time of 50,000 hours, a typical life of an electronic ballast as an example of a lighting device, the 50,000 hours composed of different duration periods of constant length. These different constant duty cycles give the in Fig. 4 squares marked entries. In the presentation of Fig. 4 Turn-on times of 20 s to 30 days were assumed. For simplicity of programming the simulation, constant duty cycles were assumed. As shown by Fig. 3 the counter reading is then increased by 1 if the random number generated in step 220 has been reached, ie on average approximately every 65535 s. Assuming that the switch-on time is constant at 10 s, the total operating time amounts to 65535 s. The probability that the count in the memory device is increased by 1 is therefore 10: 65535 = 1: 6553. In other words, every 6553 blocks in the comparison a hit is achieved, which leads to an increase of the count. If the duty cycle of 10 s is multiplied by the number 6553, the correct number of operating seconds is 65530 s.

Transferred to the example of Fig. 4 this results in 50000 hours of a 3600 s divided by the duration of 65535 s of a block resulting in 2746.62 blocks. Again FIG. 4 can be seen, between 2650 and 2810 write cycles are performed depending on the selected duty cycle. In an operating seconds counter known from the prior art, which performs a write operation every operating second, 180 × 10 ⁶ write cycles would have to be carried out. In the method according to the invention, however, the operating seconds counter comes out with a 1/65536 -stel of the write cycles. Nevertheless, the switch-on duration of a few seconds is also recorded. From the graphic of Fig. 4 shows that the operating seconds are reproduced exactly correct up to about 3% by the inventive method.

Fig. 5 shows a schematic representation of the structure of a device according to the invention. This has an input with a first input terminal E1 and a second input terminal E2, to which a mains voltage U _{N is} applied.

It comprises an electronic ballast 10, to whose output a lighting means 12 is coupled. Between the input terminals E1, E2 and the electronic ballast 10, a device 14 according to the invention is coupled. This has a device 16 for generating a random number within a predefinable value range. It further comprises a comparison device 18 coupled to the generation device 16 for comparing the random number with a predeterminable comparison number. A storage device 20 is coupled to the comparison device 18 in such a way that if the comparison of the random number with the comparison number results in a match, the count of the storage device 20 is increased by one increment.

As is apparent to one skilled in the art, the device according to the invention may also be used elsewhere than in Fig. 5 be provided shown. Thus, for example, it can be accommodated in particular in the electronic ballast 10. Furthermore, a device according to the invention can be designed to detect a plurality of statistical characteristics of a lighting device, that is, for example, the number of turn-on operations and the operating time, wherein these variables can be detected for different elements of the lighting device. In the embodiment of Fig. 5 Therefore, the statistical measures can be detected separately for the electronic ballast 10 and the lighting means 12, which can indeed be different after replacing one of the two in the event of a defect or a maintenance.

Claims (7)

1. Method for detecting a statistical characteristic of a lighting device (10; 12), comprising the following steps:

   a) generate a random number within a prescribable value range (step 120; step 220);

   b) compare the random number with a comparison number (step 140; step 260);

   c) c1) if the comparison of step b) yields a match: increase the count of a storage device (20) by one step width (step 160; step 280);

   characterized in that
   the comparison number is correlated with the count of a time measuring device that is started when the lighting device (12) is switched on.
2. Method according to Claim 1,
   characterized in that
   the comparison number is a prescribable number from the value range of step a).
3. Method according to Claim 1,
   characterized in that
   the method further comprises the following steps:

   c2) if the comparison of step b) yields no match: repeat step b) until a match is achieved, and then continue with step c1); or

   c3) if the lighting device (12) is switched off in step c2) before a match is attained: terminate the method.
4. Method according to Claim 3,
   characterized in that
   the following step is executed after step c2):

   d) wait until the count of the time measuring device has reached the value that corresponds to the maximum value of the prescribable value range of step a) (step 300); and

   continue the method with step a).
5. Method according to one of the preceding claims,
   characterized in that
   the count of the storage device (20) is continued each time after the lighting device (12) is switched off.
6. Method according to one of the preceding claims,
   characterized in that
   the step width is 1.
7. Device for detecting a statistical characteristic of a lighting device (10; 12), comprising:

   - a device for generating a random number within a prescribable value range;

   - a comparison device for comparing the random number with a comparison number; and

   - a storage device (20) that is coupled to the comparison device in such a way that if the comparison of the random number with the comparison number yields a match, the count of the storage device (20) is increased by one step width;

   characterized in that
   the comparison number is correlated with the count of a time measuring device that is started when the lighting device (12) is switched on.

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