RS63645B1 - LED LIGHT MODULE, SIGNAL LIGHT WITH SUCH LIGHT MODULE, AS WELL AS THE WORKING PROCEDURE OF SUCH LIGHT MODULE - Google Patents

Description

Description

TECHNICAL FIELD TO WHICH THE INVENTION BELONGS

[0001] The invention relates to an LED light module, a signal light with such a light module, and in particular for rail, water, air or road traffic, as well as to the operation procedure of such a light module.

STATE OF THE ART FOR THE INVENTION

[0002] Due to their properties, such as low power consumption and long service life, light emitting diodes (light emitting diodes, abbreviated LEDs) are increasingly being used as replacements for classic lighting devices, and also especially in lights that are relevant to safety, such as, e.g. traffic signals, limit lights and vehicle lights, which here means lights for all types of land, water and air vehicles.

[0003] With many lights, automated monitoring of proper functioning is desirable or even prescribed. While in the case of classic lighting devices, the monitoring of correct functioning can generally be easily realized (as a rule, it is sufficient to monitor whether the current flows or not through the lighting device; if, despite the effect of the voltage, the current does not flow through the lighting device, then the lighting device is defective and must be replaced), monitoring the functioning of LEDs is not trivial for various reasons. Then, for example, it may happen that the LED does not light up, even though current is flowing through it.

[0004] Complete LED failure can be detected by combined current and voltage monitoring. However, this method of supervision does not allow determining, for example, changes in light intensity (degradation) caused by the aging of LEDs.

[0005] It is known that LED light modules, ie. usually assemblies with multiple LEDs and other elements, such as ballast units (dimmers, ballasts) for LED operation, equipped with a run time counter, which determines the current LED run time. When a certain operating time is reached, then the LEDs change independently of whether the light they emit event. still meets the prescribed requirements or not. This procedure results in regular replacement of LEDs that are still functioning properly.

[0006] It has been shown that the aging of LEDs depends not only on their pure working time, but also on other factors, especially on the working current and working temperature.

[0007] One obvious solution to the problem of determining the reduction of emitted light caused by aging is direct monitoring of the light emitted during LED operation using appropriate sensors. For these purposes, DE 197 54 222 proposes an LED monitoring unit, in which the light emitted by the LED is measured by means of a single photosensor. If the light intensity falls below a certain threshold value then a warning signal is generated, indicating to the LED operator that the LED should be replaced.

[0008] The type of supervision known from DE 197 54 222 is associated with very large material costs, especially in the case of the so-called route signaling for rail traffic, because the monitoring unit is powered by its own operating voltage, whereby the corresponding cables often have to be run several hundred, and sometimes a thousand and more meters from the appropriate connection point to the monitoring unit.

[0009] US 6,078,148 describes a control for a transformer with primary and secondary coils, with a plurality of windings and connections for changing the number of active windings, and thus the light emission of the LED. For these purposes, the connections are managed depending on one operating parameter of the LEDs in order to maintain the light emission of the LEDs above a previously determined level based on a combination of voltage and current measurements on the LEDs.

[0010] EP 0 974 947 A1 shows a light signaling system with at least one signal generator, whose light source is derived from LEDs arranged in the form of a matrix and with a monitoring device intended for monitoring the light-emitting diodes in their operating state without defects, and which has a light sensor placed on the path of the light beam of the LEDs, as well as with an evaluation device intended for comparing the light sensor signal, which is generated by the light sensor with a predetermined to the desired value corresponding to the normal operating state of light emitting diodes.

[0011] DE 10 2005 032 719 A1 shows a light signaling system with a signal generator containing at least one light-emitting diode intended for emitting a light signal, with a control device for activating, evaluating and monitoring the signal generator, with power supply conductors and data transmission conductors between the control device and the signal generator, and with a switching device for turning on the signal generator, by being placed in the immediate vicinity of each signal generator one switching device, wherein the signal transmitters are connected to the control device via a conductive cable having conductors for power supply and conductors for data transmission.

[0012] According to DE 10 2010 026 012 A1, a signal transmitter for generating light points of different colors with RGB-LEDs has an optical sensor for safe monitoring of the location of the color and light intensity of the signal transmitter, from the point of view of signaling technology.

[0013] DE 10 2010 013 310 A1 shows the output circuit for driving the fan, which is connected to the output of the ballast device, in order to supply the light module with electricity, whereby both the fan and the control circuit are connected to the output circuit to supply electricity.

[0014] WO 2014/179379 A1 and WO 2009/116854 A2 describe a suitable LED light module according to the preamble of claim 1. US 8,159,146 B1 describes an LED drive device with pulse width modulation.

THE ESSENCE OF THE INVENTION

[0015] The invention aims to realize an LED light module with a monitoring unit, as well as a signal light equipped with it, where the monitoring unit can be made functional with minimal material consumption and therefore in a particularly economical way.

[0016] The invention also aims to realize the operation procedure of the LED light module, which could be performed in an economical way while simultaneously ensuring high reliability of operation.

[0017] These goals are achieved by means of an LED light module with characteristics according to claim 1, a signal light with characteristics according to claim 4, or. procedure with characteristics according to requirement 3.

[0018] The LED light module according to the invention does not require a special power supply for the monitoring unit, but it can use the current that supplies the light module with pulse width modulation, in order to monitor the intensity of the emitted light, and thanks to this, the complex calculation of the share of scattered light, which is performed by the usual monitoring units, is omitted. These and other advantages will be apparent from the following, purely illustrative and non-limiting description of an exemplary embodiment associated with the drawings, which consists of two drawings of the drawings.

BRIEF DESCRIPTION OF THE DRAFT PICTURES

[0019]

Figure 1 is a highly schematic block diagram for a basic understanding of the operation of the invention.

Fig. 2 is a highly schematic example of the embodiment of the light module according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0020] Figure 1 shows very schematically the basic idea of the invention, according to which a strip 10 of serially connected LEDs of a suitable LED light module, and in particular a light module for signal lights for road and rail traffic, is supplied with current with a certain voltage in a known manner via the conductor 12, and then a part of the supplied current via a connection that is parallel to at least some of the LEDs of the strip is used for the operation of the monitoring unit 14. The monitoring unit 14 can determine the appropriate operating parameters of the light module, such as e.g. the current flowing through the strip during operation, the voltage drop on the strip, the temperature in the strip's environment and the light intensity generated by the strip, and it sends the characteristic values for these operating parameters to the superior unit 16 for evaluation.

[0021] The monitoring unit 14 can be fully powered by the power supply of the LED strip, so that a separate power supply is primarily omitted and thanks to this, especially when the light module is used in signal lights for rail traffic, in some cases significant amounts of cables can be saved. Means, such as a voltage meter for the ballast voltage of the LEDs, may be provided, which are connected in parallel to one or more LEDs 18 of the strip 10. These means may be powered by the power supply of the LEDs 20 during operation of the light module.

[0022] If the superior unit 16 for evaluation is powered via the power supply of the LED-strip, then, accordingly, the detection of scattered light is avoided, especially in the case of the LED-strip that is switched off on impulse. Modern components that are necessary for that, such as e.g. the temperature or photosensor, as well as the microcontrollers, have such a low current consumption that they have no measurable effects on the light intensity of the LED-strip, when part of the current for powering the units 14 and 16 is drained via the mentioned parallel connection.

[0023] Typically the LED strip 10 of the type in question has e.g. eight series-connected LEDs with a current consumption of 350 mA, while the photosensor, as a means of determining the next operating parameter, and the corresponding microcontroller for evaluating the photosensor signal have a current consumption in the area of about 1 to 2 mA. It has been shown that the circuit according to the invention works particularly well if the current consumption of units 14 and 16 is more than 20 times lower than the current consumption of the LED strip, and primarily about 50 to 100 times lower.

[0024] Figure 2 shows an example of the implementation of the invention, where two operating parameters are determined here and are used for monitoring and controlling the LED strip in the manner according to the invention. The units corresponding to the units in Figure 1 are marked with the same call signs used in Figure 1.

[0025] The light module shown in this embodiment forms one unit, which in particular can be used as a signal light and can be externally supplied with current via a conductor 12. The LED strip here is formed by several serially connected LEDs 18, of which only a few are shown here, whereby the supply voltage and current are controlled by the ballast unit 20. In this embodiment, the ballast unit 20 is part of the light module, as is the unit 16 for the built-in evaluation, but it can also be, just like the evaluation unit 16, placed outside the mentioned light module. The evaluation unit 16 and the ballast unit can be part of a single control unit.

[0026] As shown by the conductor 22, the monitoring unit 14 is supplied with current in the first place via a connection parallel to the serial connection of the LEDs 18, whereby the various rectangular signals symbolically shown in the figure should indicate that the current is pulse width modulated.

[0027] As shown by means of the corresponding circuit diagram, the monitoring unit 14 in this exemplary embodiment contains a photosensor 24, which is placed in the light module and determines a value that is proportional to the light intensity generated during the operation of the LEDs. In light modules of the type in question here, the LEDs are typically arranged rotationally symmetrically, and the light module is equipped with a front or diffusing plate, thanks to which part of the emitted light is reflected back, which can then be detected by the photosensor 24.

[0028] In this embodiment, the monitoring unit 14 further contains two voltage meters 26, which together with the corresponding shunt resistors 28 and conductors 30 enable indirect current measurement of the current that flows through the LED strip during operation.

[0029] It is not shown, but in one preferred embodiment a voltage meter is provided that measures the entire voltage drop on the LED strip, which can be suitable especially for light modules for use in signal lights for rail traffic. The advantages of combined current-voltage monitoring in monitoring LED strips are known and, for example, are described in EP 1 992 524 A2, the contents of which are incorporated herein by reference. In one variant embodiment of the invention, the means provided for determining the current and/or voltage can be supplied with current in pulses via the current supply of the LEDs.

[0030] The values for the current current, i.e. the current currently flowing through the LED-strip, presented by the voltage meters 26, and the value proportional to the intensity of the light emitted by the LEDs during operation, measured by the photosensor 24, are sent to the evaluation unit 16, which in this embodiment contains a microcontroller 32 and a regulator 34, which is adapted to send a control value to the ballast unit 20. It should be emphasized that the unit The evaluation unit 16 is not supplied, as in previously known light modules, by its own power supply, but primarily, like the monitoring unit 14, by the current that supplies the LEDs 18. If the photosensor now detects, for example, that the intensity of the light emitted during operation has decreased due to the degradation of the LEDs 18, then the evaluation unit 16 can generate a corresponding control signal, by means of which the ballast unit 20 is instructed to increase the current leads to LEDs, so that it is obtained desired light intensity. With the above boundary condition that the current consumption by the monitoring unit 14 and the evaluation unit 16 is significantly less than the current consumption of the LEDs, the decrease in the brightness of the LEDs due to the current drain can be ignored, especially since the photosensor 24 detects it anyway and leads to current regulation again.

[0031] The evaluation unit 16 is adapted to directly or indirectly control the current supplied to the LED strip depending on the so-called of the "next working parameter", which here is the light intensity, either as part of a complex control circuit that acts directly on the current or by communicating with a special unit, which here is the ballast unit 20 and transmits this information to it, which is the basis for current management, and thus indirectly controls the current.

[0032] In the example of the implementation shown in Figure 2, the current determination of the current is two-channel, which means that it is performed redundantly, so that measurement errors are practically excluded, because the microcontroller 32 can be implemented in such a way that it can generate a corresponding error message in the event of a deviation between the two signals representing the current current, which can then be transmitted to a superior place such as, for example, a maintenance center in a way that is known as such.

[0033] In addition to the already mentioned provision of a stable location of colors, the operation with the modification of the pulse width, which is provided in one preferred embodiment of the invention, has two further significant advantages. Consequently, in those cases in which the means for determining at least one subsequent operating parameter comprise a photosensor as in Figure 2, a complex calculation of the proportion of scattered light is not necessary, since the sensor, thanks to the LED current supply according to the invention, only works when the LEDs are also switched on, in which case the proportion of scattered light can be ignored. The light, which falls on the sensor when the LEDs are off between two current pulses, is not included in the usual quantification by the sensor, so standard photosensors that are not expensive can be conveniently used, which in order to send the measured value perform the quantification of the light over a certain period of time.

[0034] The next advantage of working with pulse width modulation is that the evaluation unit 16 can examine whether the photosensor 24 or the voltage meter 26 sends signals during the time between two current pulses, on the basis of which the malfunction of the photosensor and/or the voltage meter can then be determined and, in a manner known as such, can generate a corresponding error message. Accordingly, the evaluation unit 16 practically has the function of testing means for determining at least one of the following operating parameters. It also examines whether the signals sent by the current meter and/or photosensor have a shape that matches the shape of the pulse width modulated current.

[0035] Within the concept of the invention, numerous modifications and improvements are possible, which are particularly related to the type and number of means for determining the operating parameters of LEDs. Thus, in one preferred embodiment of the invention, it is intended to determine the temperature in the environment of the LEDs of the strip, whereby the fan can be turned on, for example, by means of this value via the evaluation unit. Also, such a fan can primarily be powered by the operating current of the LEDs, since in typical cases of application the fan must have only a small power.

[0036] The invention in a particularly simple and cheap way for the first time enables the realization of very safe monitoring of the correct functioning of the LED light module, since three different monitoring methods can be combined - monitoring the voltage drop on the LED strip, monitoring the current flowing through the strip and determining a value that is proportional to the intensity of the emitted light.

LIST OF CALL SIGNS

[0037]

10 LED strips

12 conductor

14 monitoring units 16 evaluation units 18 LEDs

20 ballast units

22 conductor

24 photosensor

26 voltage meter

28 shunt resistors

30 conductors

32 microcontroller

34 regulator

Claims (4)

Patent claims 1. LED light module, especially for signal lights for road and rail traffic, which contains - at least one strip (10) of serially connected LEDs (18), - means for monitoring (26, 28, 30) the current that flows through the tape during operation of the tape and/or the voltage drop on the tape, - power supply (20) LEDs, - a monitoring unit (14), which contains means for determining at least one other operating parameter of the LED, which contain a sensor (24) for determining a value that is proportional to the intensity of the light emitted during the operation of the light module and for sending a signal based on that value, and an evaluation unit (16), which is adapted to control the current supply (20) of the LEDs for the current with which the LED strip is fed depending on the signal by means of pulse width modulation, indicated by, which during the operation of the light module, the monitoring unit (14) is also supplied with current via the current supply (20) of the LEDs (18) in accordance with the pulse width modulation. 2. LED light module according to claim 1, characterized in that the evaluation unit (16) has the function of testing means for determining at least one other operating parameter. 3. The operation procedure of the LED light module, especially for signal lights for road and rail traffic, whereby - the light module has a strip (10) of sequentially connected LEDs, - the current that flows through the tape during operation and/or the voltage drop on the tape is monitored, - using the sensor (24) of the monitoring unit (14), a value is determined that is proportional to the intensity of the light emitted during the operation of the light module, and based on that value, a signal is sent to the superior unit (16) for evaluation and that the current supplied to the strip during operation is controlled depending on that value by modulating the pulse width of the LED current supply, indicated by the fact that during operation of the light module, the monitoring unit (14) is also supplied with current via the current supply of the LEDs in accordance with the pulse width modulation. 4. Signal light, especially for road and rail traffic, indicated by the fact that it contains an LED light module according to claim 1 or 2.