EP3165053B1 - Apparatus and method for monitoring a signal transmitter of a traffic control signal installation, which signal transmitter comprises a light-emitting diode - Google Patents

Description

The invention relates to a device and a method for monitoring a signal transmitter comprising a light-emitting diode of a traffic signal system. The invention further relates to a traffic signal system and a computer program.

In the known LED ("light emitting diode", light emitting diode) signal generators of traffic signal systems usually only electrical parameters are measured. A reduction in the brightness of the LED and the resulting compliance with the standards with respect to the minimum light requirements can not be detected. Therefore, it is necessary to replace the LED signal generator as a precautionary measure at specified intervals.

A disadvantage of this is in particular that due to the specified replacement intervals, an LED signal transmitter is also replaced, if this is not necessary, the LED signal transmitter so still emits light with a sufficient intensity. This causes unnecessary costs, increased maintenance and unnecessary material costs.

The publication WO 2007/006684 A1 shows a traffic signal.

The publication WO 2004/070675 A2 shows an LED module for an LED traffic signal.

From the publication DE 10 2010 005 088 A1 is a light signal, in particular railway light signal, with at least one LED known, wherein means for fail-safe measurement and control of the light intensity are provided to a predetermined target value.

The publication EP 2 677 387 A1 shows a light signal arrangement, in particular a railway light signal arrangement.

The publication DE 10 2010 026 012 A1 shows a LED light signal.

The publication DE 102 08 462 A1 shows a lighting arrangement.

The object underlying the invention is to provide a device for monitoring a light emitting diode comprehensive signal generator for a traffic signal system, which overcomes the known disadvantages.

The object on which the invention is based is furthermore to be seen in providing a corresponding method for monitoring a signal transmitter comprising a light-emitting diode (for example a traffic signal system).

The object underlying the invention is further to be seen in a corresponding signal generator (for example, for a traffic signal system) specify.

The object underlying the invention is further to be seen in specifying a corresponding computer program.

These objects are achieved by means of the subject matter of the independent claims. Advantageous embodiments of the invention are the subject of each dependent subclaims.

According to one aspect, there is provided an apparatus for monitoring a signal emitting device comprising a light emitting diode, comprising: a measuring device for measuring an actual light intensity of the light emitted by the diode and measuring at least one electrical characteristic of the diode and a two-channel control device for Operating the signal generator depending on the measured actual light intensity and the measured electrical characteristic.

According to another aspect, there is provided a method of monitoring a light emitting diode signal generator (eg, a traffic signal system) comprising the steps of: measuring an actual light intensity of the light emitted by the diode and at least one electrical characteristic of the diode and operating the signal generator depending on the measured actual light intensity and the measured electrical characteristic.

In yet another aspect, there is provided a signal generator comprising: a signal chamber comprising a light emitting diode; and an apparatus for monitoring a signal transmitter of a traffic signal system comprising a light emitting diode.

According to a further aspect, a traffic signal system comprising the signal generator according to the invention is provided.

In yet another aspect, there is provided a computer program comprising program code for performing the method of monitoring a light emitting diode signal generator comprising a light emitting diode when the computer program is executed on a computer, preferably on a controller.

In particular, the invention thus encompasses the idea of measuring an intensity of the light which is emitted by means of the diode. The result of the measurement, ie the actual light intensity, is used as a criterion for operating the signal generator. This means that the signal generator is operated depending on the measured actual light intensity. The monitoring of the signal generator is thus in particular an optical monitoring. As a result, in particular, the technical advantage is achieved that can be detected when the legal minimum light requirements can no longer be met due to a reduction in the brightness of the light-emitting diode, for example, due to aging or a high ambient temperature. It can thus also be determined in an advantageous manner, whether the light-emitting diode must be replaced or not. It therefore requires no more defined replacement intervals. This advantageously reduces service costs, further reduces costs and reduces material costs.

The invention further includes the idea that in addition to the optical monitoring nor an electrical monitoring is performed, insofar as in addition to the measurement of the actual light intensity at least one electrical characteristic of the diode is measured, in which case based both on the measured actual light intensity and on the electrical characteristic, the diode is operated. As a result, the technical advantage, in particular, is achieved that efficient monitoring can be carried out.

In particular, by monitoring both the actual light intensity and the electrical parameter (s), a higher reliability and a higher level of safety are achieved in an advantageous manner. Because a measurement of the electrical parameter alone is still no statement as to whether there is enough light for proper or proper operation, or even if light is still emitted.

The fact that the control device has two channels has in particular the technical advantage that a high degree of safety can be ensured. Because of the two-channel nature, the two channels can monitor each other, in particular monitor for errors.

For example, the control device comprises two processors (first and second processors, as described below), which are designed, for example, to monitor each other, in particular to monitor for errors. In the case of an error, according to one embodiment, it is provided that both processors independently of one another, the signal generator, in particular, the light signal system, for example, turn off the diode. This, for example, via an electronic switch, which produces a short circuit when switching, so is designed to produce a short circuit during switching, the short circuit triggers a backup of the controller upstream. In other words, in the case of a fault, both processors independently of one another have the possibility of producing a short circuit via the electronic switch which triggers the upstream backup.

The operation of the signal generator comprises, according to one embodiment, a driving of a driver circuit of the diode. The driver circuit may also be referred to as an LED driver. That is, according to one embodiment, it is provided that the control device is designed to control a driver circuit of the diode. The driver circuit includes, for example, a power driver.

The driving of the driver circuit according to an embodiment comprises that the driver circuit is driven so that an actual light intensity is increased or decreased, generally that an actual light intensity is set or regulated to a predetermined target light intensity.

The at least one electrical parameter includes, for example, an electrical current and / or an electrical voltage. That is, for example, measuring an electric current that flows through the diode during operation. For example, in addition to or instead of an electrical voltage is measured, which is applied to the diode in operation or is applied to the diode.

The light-emitting diode can also be abbreviated as LED below. Here, LED stands for the English terms "light emitting diode".

A signal generator in the sense of the present invention comprises in particular one or more signal chambers, in which preferably the one or more LEDs are arranged.

If written in the light of the description of LEDs of the signal generator, so it is always included the case that this is the LEDs of the signal chambers or the signal chamber.

If written in the light of the description of a signal generator of a traffic signal, so it is always the case includes that only the signal generator is disclosed as such, that is detached from the traffic signal. The phrase "signal generator of a traffic signal system" thus also includes the following: Signal generator for a traffic signal system.

According to one embodiment, the signal transmitter comprises a plurality of light-emitting diodes. The versions in connection with a LED apply analogously to several LEDs and vice versa. The monitoring of several LEDs is carried out analogously to the monitoring of an LED.

According to one embodiment, the traffic signal system comprises a plurality of signal transmitters each comprising one or more light-emitting diodes. The monitoring of these multiple signal generator is carried out analogously to the monitoring of a signal generator. The corresponding explanations apply analogously.

In an embodiment, it is provided that the control device comprises a first processor and a second processor, wherein the first processor is designed to control a driver circuit of the diode based on the measured actual light intensity and the measured electrical characteristic, wherein the second processor is configured, To monitor the first processor in operation for an error and to turn off the diode in case of a detected error.

This has the technical advantage in particular that an error in the first processor does not lead to damage to the diode.

According to one embodiment, it is provided that a separate voltage regulator is provided for each of the two processors for a respective electrical voltage supply of the two processors.

As a result, the technical advantage in particular that causes a failure of a voltage regulator does not mean that both processors can not be supplied with electrical voltage.

According to a further embodiment, it is provided that the second processor is designed to switch off the diode for a functional test of the first processor, wherein the second processor is designed to prevent a restart of the diode in the absence of error message of the first processor that the diode does not work ,

As a result, in particular, the technical advantage is achieved that the first processor can be checked for malfunction efficiently. Because if the first processor works properly, it would have the diode off due to the measured actual light intensity and the measured electrical characteristic (both of which should yield zero in the measurement accuracy) recognize and issue a corresponding error message that the diode is not working. If the first processor does not do this, the second processor assumes that the first processor has a fault and, for safety reasons, has the diode switched off, thus preventing the diode from being switched on again.

According to another embodiment, it is provided that the first processor is designed to send a data packet to the second processor and to switch off the diode in the absence of a response packet of the second processor, and / or that the second processor is configured to send a data packet to the first processor and to switch off the diode in the absence of a response packet of the first processor.

As a result, in particular, the technical advantage is caused that the two processors can monitor each other efficiently, so can check each other for functionality. For example, the first processor sends a data packet to the second processor. If, within a predetermined time after the transmission of the data packet, no response (response data packet) comes back from the second processor, ie if a response data packet fails within the predetermined time, the first processor assumes that the second processor has an error and switches off the security for security reasons Diode off. The same applies to the reverse case: The second processor sends a data packet to the first processor.

In one embodiment, it is provided that the first and / or the second processor is designed or are in the event of a fault, the signal generator, in particular the diode turn off, in particular irreversible turn off. The irreversible shutdown includes, for example, triggering a fuse (blowing the fuse) in an electrical circuit of the signal generator, in particular in an electrical circuit of the diode.

For example, the first and / or the second processor are respectively designed to generate an EOL signal in the event of an error in order to irreversibly switch off the signal generator, in particular the diode. "EOL" stands for "End of life".

The error case includes in particular that the first and / or the second processor has detected an error or have. The error may have occurred in one of the two processors, for example.

According to one embodiment, it is provided that the control device is designed to regulate the actual light intensity to a predetermined, larger setpoint light intensity if the measured actual light intensity is smaller than a predetermined light intensity threshold value. As a result, in particular, the technical advantage is achieved that a minimum light intensity is always radiated insofar as the predetermined desired light intensity is controlled when the measured actual light intensity is smaller than the predetermined light intensity threshold value. The predetermined larger target light intensity usually corresponds to the minimum light intensity according to the legal requirements. "Greater" here refers in particular to the fact that the predetermined target light intensity is greater than the measured actual light intensity. That is, the light intensity of the emitted light is increased when the measured actual light intensity is smaller than a predetermined light intensity threshold.

According to one embodiment, it is provided that the control device is designed to switch off the signal generator if the actual light intensity can not be regulated to the predetermined desired light intensity. As a result, in particular, the technical advantage is effected that it is avoided that the signal generator is still operated even if a predetermined brightness can not be achieved. As a result, standards with respect to the minimum light requirements can be maintained in an advantageous manner. In particular, it is provided that the traffic signal system is switched off or passes into an error state. In particular, it is provided that an error signal is formed, which can be sent to a central control computer, for example, so that it can be determined that the traffic signal system no longer operates correctly.

According to a further embodiment, it is provided that the measuring device comprises a light sensor and the control device comprises a processing device, which is formed is to subtract a measured by means of the light sensor with the diode off light signal from a measured by the light sensor with the diode switched light signal to form a subtracted light signal corresponding to the measured actual light intensity. As a result, in particular the technical advantage is achieved that, when the diode is switched off, an extraneous light component can be measured, so that when the diode is switched on, the luminous flux of the LED can be calculated by a simple subtraction. As a result, an external light component in the light signal can thus be advantageously eliminated. This advantageously increases a signal-to-noise ratio.

The processing device according to one embodiment comprises the first and / or the second processor.

For example, the first and / or the second processor are respectively designed to subtract the light signal measured by the light sensor with the diode switched off from the light signal measured by the light sensor with the diode switched on in order to form the extracted light signal which corresponds to the measured actual light intensity ,

For example, the first and / or the second processor are respectively designed to switch off the signal generator, in particular the diode, if the actual light intensity can not be regulated to the predetermined desired light intensity.

According to one embodiment, it is provided that the control device is designed to periodically switch the diode on and off for measuring the light signals when the diode is switched off and on, the period being in the millisecond range. So a lock-in measurement is performed. As a result, in particular, the technical advantage is achieved that can be reliably determined that the detected light is really from the LED and not by externally penetrating light (extraneous light). For as it is known when the LED should light up or not, this can be checked in accordance with the measured light signal. The period is in the millisecond range, since here a human eye is usually too lazy to detect this periodic switching on and off. Thus, the monitoring, so the measurement can be carried out undisturbed during normal operation of the traffic signal system.

For example, according to one embodiment, it is provided that the first and / or the second processor is / are configured to periodically switch the diode on and off for measuring the light signals when the diode is switched off and on, the period lying in the millisecond range.

According to a further embodiment it is provided that a temperature sensor is provided for measuring a temperature of an environment of the signal generator, wherein the control device is designed to operate the signal generator depending on the measured temperature. As a result, the technical advantage in particular that a further characteristic variable can be used for the operation of the signal generator. As a result, the signal generator can be operated even better in an advantageous manner. In particular, it can thus be recognized whether an excessively low luminous flux is due to an excessively high ambient temperature. Too high an ambient temperature here means, in particular, that there is an ambient temperature that is outside the specification of the LED. Of course, this also applies to too low temperatures.

For example, in one embodiment, the first and / or the second processor is configured to drive a driver circuit of the diode based on the measured temperature.

In one embodiment, it is provided that the first and / or the second processor is / are configured to drive a driver circuit of the diode based on the measured actual light intensity and based on the measured electrical characteristic.

In one embodiment, the first and / or second processor are respectively designed as microcontroller (μC).

According to a further embodiment it is provided that the measuring device comprises a light sensor, wherein a light guide is provided for guiding a part of the emitted light towards the light sensor. As a result, in particular the technical advantage is effected that the measuring location can be different from the location or the position of the LED. This means that the light sensor can be arranged independently of the light-emitting diode. This advantageously causes a high flexibility in the construction of the signal generator.

According to one embodiment, it is provided that the measuring device comprises a light sensor. The light sensor is in particular a photodiode. In particular, a plurality of light sensors, in particular a plurality of photodiodes, are provided.

In an embodiment, it is provided that the device for monitoring a signal transmitter comprising a light-emitting diode for a traffic signal system is designed or set up to carry out or carry out the method for monitoring a signal transmitter comprising a light-emitting diode for a traffic signal system.

In an embodiment it is provided that the method for monitoring a light emitting diode signal transmitter comprising a light emitting diode is carried out or carried out by means of the device for monitoring a light emitting diode signal generator comprising a light emitting diode.

Technical functionalities of the device arise directly from corresponding functionalities of the method and vice versa.

In one embodiment, it is provided that the operation comprises driving a driver circuit of the diode by means of a first processor based on the measured actual light intensity and the measured electrical parameter, wherein the first processor is monitored for an error during operation by means of a second processor wherein the second processor turns off the diode upon a detected fault.

In a further embodiment it is provided that a respective electrical power supply for the two processors is provided by means of a separate voltage regulator.

According to another embodiment, it is provided that the second processor switches off the diode for a functional test of the first processor and, in the absence of an error message of the first processor, that the diode does not work, prevents the diode from being switched back on.

According to a further embodiment, it is provided that the first processor sends a data packet to the second processor and switches off the diode in the absence of a response packet of the second processor and / or wherein the second processor sends a data packet to the first processor, and if the response packet of the first processor fails, the Diode turns off.

According to one embodiment, it is provided that the operation comprises regulating the actual light intensity to a predetermined larger desired light intensity if the measured actual light intensity is smaller than a predetermined light intensity threshold value.

According to another embodiment, it is provided that the signal generator, in particular the traffic signal system, is switched off when the actual light intensity can not be regulated to the predetermined desired light intensity.

According to yet another embodiment, it is provided that a light sensor is used for measuring, whereby a light signal measured by the light sensor with the diode switched off is subtracted from a light signal measured by the light sensor with the diode switched on in order to form a subtracted light signal which corresponds to the measured actual signal. Light intensity corresponds.

According to a further embodiment, it is provided that for measuring the light signals when the diode is switched off and on, the diode is periodically switched on and off, the period being in the millisecond range.

According to another embodiment, it is provided that a temperature of an environment of the signal generator is measured and the signal generator is operated depending on the measured temperature.

According to yet another embodiment it is provided that a light sensor is used for measuring and a part of the emitted light is guided by means of a light guide to the light sensor.

Embodiments relating to the method are analogous to embodiments with respect to the device and vice versa. Corresponding statements, technical advantages and features with regard to the method apply analogously to the device and vice versa.

FIG 1

eine Vorrichtung zum Überwachen eines eine lichtemittierende Diode umfassenden Signalgebers einer Lichtsignalanlage,

FIG 2

ein Ablaufdiagramm eines Verfahrens zum Überwachen eines eine lichtemittierende Diode umfassenden Signalgebers einer Lichtsignalanlage,

FIG 3

einen Signalgeber,

FIG 4

eine Auswertung eines mittels einer Fotodiode gemessenen Lichtsignals und

FIG 5

eine weitere Vorrichtung zum Überwachen eines eine lichtemittierende Diode umfassenden Signalgebers einer Lichtsignalanlage

zeigen.The above-described characteristics, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of the embodiments which will be described in connection with the drawing

FIG. 1

a device for monitoring a signal transmitter comprising a light-emitting diode of a traffic signal system,

FIG. 2

a flowchart of a method for monitoring a signal transmitter comprising a light emitting diode of a traffic signal system,

FIG. 3

a signal generator,

FIG. 4

an evaluation of a measured by a photodiode light signal and

FIG. 5

a further device for monitoring a signal transmitter comprising a light-emitting diode of a traffic signal system

demonstrate.

Hereinafter, like reference numerals may be used for like features.

FIG. 1 shows an apparatus 101 for monitoring a signal emitting device comprising a light-emitting diode of a traffic signal system (not shown).

The device 101 comprises a measuring device 103 for measuring an actual light intensity of the light emitted by the diode and for measuring at least one electrical parameter of the diode. For example, the measuring device 103 comprises a light sensor, preferably a photodiode. The measuring device 103 comprises, for example, a voltage sensor and / or a current sensor.

The device 101 further comprises a dual-channel control device 105 for operating the signal generator as a function of the measured actual light intensity and as a function of the measured electrical parameter.

In an embodiment not shown, the device 101 comprises a light guide for guiding a part of the emitted one Light towards the measuring device 103, preferably to the light sensor.

FIG. 2 shows a flowchart of a method for monitoring a signal transmitter comprising a light-emitting diode of a traffic signal system.

According to a step 201, an actual light intensity of the light emitted by the diode and at least one electrical characteristic of the diode are measured. The measurement of the actual light intensity and the measurement of the at least one electrical parameter are carried out, for example, at the same time or preferably one after the other. In a step 203, the signal generator is operated as a function of the measured actual light intensity and as a function of the measured electrical parameter.

The at least one electrical parameter includes, for example, an electrical current and / or an electrical voltage. The measured parameters are used as a further basis for the operation of the signal generator. This means that the signal generator is operated in addition to the measured actual light intensity based on the one or more measured electrical parameters.

FIG. 3 shows a signal generator 301 (for example, a traffic signal system).

The signal generator 301 comprises three signal chambers 303, 305, 307, each of which comprises at least one, preferably a plurality of light-emitting diode. The signal generator 301 further comprises in each case a device 101 according to FIG FIG. 1 for the three signal chambers 303, 305, 307. For the sake of clarity, the measuring device 103 and the control device 105 are in FIG FIG. 3 not shown. The signal generator 301 is comprised, for example, by a traffic signal system.

The device 101 monitors the respective light-emitting diodes of the three signal chambers 303, 305 and 307 by measuring corresponding actual light intensities and electrical characteristics so that the diodes of the individual signal chambers 303, 305 are then based on the measured actual light intensities and the measured characteristics , 307 are operated.

FIG. 4 shows an evaluation of a light signal, which was measured by means of a photodiode.

Plotted is the intensity I of the measured light signal over the time t. From time t0 to t1, the diode of the signal generator is turned on. A light intensity I1 is measured. This is usually composed of the light emitted by the diode and an ambient light of the diode. In order to deduct the proportion of extraneous light, ie the ambient light, it is provided that in the time interval between t1 and t2, the diode is turned off. This time interval is in the microsecond range. Thus, a light intensity I2 is measured when the diode is turned off. The diode is switched on again after the time t2. It is preferably provided that the switching on and off is performed periodically. The time interval is identified by the reference numeral 401.

The actual light intensity, that is to say the light signal which originates exclusively from the photodiode, now results from the subtraction I2 of I1. The subtracted signal is symbolically represented here by means of a double arrow, with "I3" pointing to this double arrow as a sign that this is the actual light intensity of the light of the diode.

FIG. 5 shows a further device 501 for monitoring a signal transmitter comprising a light-emitting diode of a traffic signal system.

The device 501 comprises a two-channel control device 503. The two-channel control device 503 comprises a first processor 505 and a second processor 507, which are designed, for example, as a microcontroller (.mu.C). The first processor 505, for example, performs the main tasks in the monitoring, can be referred to as a master. The second processor 507 takes over in particular monitoring functions and can thus be referred to in particular as an "observer", ie observer or supervisor.

The first processor 505 assumes, for example, a drive 509 of an LED driver 511 (driver circuit) of an LED 513 of a signal transmitter, not shown here, of a light signal system likewise not shown here. The driving 509 of the LED driver 511 comprises, for example, a pulse width modulation (PWM). Further, the first processor 505 measures an LED current 515 and an LED voltage 517. The second processor 507 may also take over the aforementioned drive. This is symbolically indicated by an arrow with the reference numeral 510.

The device 501 further comprises a photodiode 519 which is connected to an amplifier 521 which generates from the incident light on the photodiode 519 an electric voltage equivalent to the light.

The photodiode 519 measures a light intensity of the light emitted by the LED 513. The first processor 505 evaluates the electrical voltage signal of the amplifier 521. In this case, therefore, an electrical voltage signal is transmitted from the amplifier 521 to the first processor 505, which corresponds to the measured light intensity. The voltage signal is symbolically indicated by an arrow with the reference numeral 523.

The first processor 505 and the second processor 507 communicate with each other. In particular, the first communicates Processor 505 with the second processor 507 to see if it is still working properly. The particular as follows:
For example, the first processor 505 initiates communication or initiates communication by sending a data packet to the second processor 507. If the second processor 507 does not receive a valid data packet from the first processor 505 within a certain time to initiate communication, it assumes that the first processor 505 is no longer functioning properly. When the second processor 507 receives the data, it sends its data back on the return channel. The valid data packet (the returned data) causes the first processor 505 to recognize that the second processor 507 is operating correctly.

The communication between the two processors 505, 507 is symbolically indicated by a double arrow with the reference numeral 525 and is performed, for example, via a Serial Peripheral Interface (SPI), which is a bus system.

The first processor 505 is also designed to switch off the signal generator, in particular the traffic signal system. In particular, the first processor 505 limits an input current for the LED 513. In particular, the first processor 505 irreversibly switches off the signal generator, in particular the traffic signal system, in the event of an error.

The tasks of the second processor 507 are, for example, the following:
A communication with the first processor 505 to see if it is still working properly. In particular, the second processor 507 checks a signal path of the light information to the first processor 505 via a "Monitor Validation Test". In case of an error the second one switches Processor 507 the signal generator, in particular the traffic signal, irreversibly.

The "Monitor Validation Test" is carried out in particular as follows:
Here, the photodiode 519 is short-circuited by the second processor 507. As a result, the first processor 505 no longer measures voltage from the amplifier and must report this as an error to the observer (second processor 507). If no errors are reported, the second processor 507 triggers an EOL signal (EOL = End of Life: Prevents the signal generator from being switched back on in the event of an error.). If the error is reported, the second processor 507 causes the error to be taken back by the first processor 505. That is, for example, the first processor 505 is instructed by the second processor to discard the error.

Both processors 505, 507 have their own voltage regulator 527 and 529, respectively. That is, both processors 505, 507 are powered by their own voltage regulator 527, 529 so that failure of a voltage regulator 527, 529 does not affect both processors 505, 507 simultaneously ,

The current limit on the part of the first processor 505 is controlled by a switch 531 which is connected in parallel with a resistor 533.

The current limit works in particular as follows:
At the switch-on time, a series resistance (resistor 533) is present in the supply line and limits the charging current of the capacitors of the photodiode 513. After a certain time (in the millisecond range, preferably 1 ms to 10 ms), an electronic switch is closed, bridging the series resistor 533 (FIG. low-impedance short circuits).

In the event of a fault, both processors 505, 507 have independently of each other the possibility of producing a short circuit via a respective EOL signal 535 and 537 (EOL = End of Life: in the event of a fault, preventing re-activation of the signal generator) triggers. That is, the first processor 505 may send out an EOL signal 535. The second processor 507 may transmit an EOL signal 537 in the event of an error.

The reference numeral 541 points to a connector (connector), to which an electrical supply line can be connected or plugged.

The individual function blocks according to the block diagram of FIG. 5 are divided again for the sake of clarity. The elements according to the frame 545 are associated with the diode. The elements according to the frame 547 are associated with a voltage or power supply for the device 501.

The invention thus encompasses in particular the idea of no longer based solely on monitoring the voltage of a signal generator comprising a light-emitting diode, but rather of recording the optical monitoring of the light and additionally, in particular, the electric current through the LED into a disconnection decision. For if, for example, only the electric current is monitored, there is a considerable potential for danger. Because LEDs lose their brightness with increasing age and / or thermal load at the same power consumption. This means that just by monitoring the current consumption, it can not be guaranteed that the LED will continue to emit light with the same brightness.

According to the invention, therefore, in particular a part of the LED light is deflected for example via a light guide to a photodiode and evaluated there.

In order to reliably determine that the detected light actually originates from the LED and not through externally penetrating light (extraneous light), in one embodiment the LED is periodically switched off for a very short period of time (millisecond range). This transition from "bright phase" (switched on LED) to "dark phase" (switched off LED) is measured. The results indicate whether the light originates from the LED and how high the luminous flux (brightness) is in the "bright phase". The "dark phase" has the further advantage that in this time the external light component can be measured, and thus the luminous flux of the LED can be calculated by simple subtraction (cf. FIG. 4 ). And in the case of too low luminous flux, for example due to high ambient temperature or aging, is provided according to one embodiment, readjust the brightness.

To ensure a high level of security, two microprocessors are used, which monitor each other (cf. FIG. 5 ).

Both processors are powered by their own voltage regulator according to one embodiment, so that a failure does not affect both processors simultaneously. One of the processors is, for example, the master processor (master). The other, for example, the observer processor (Observer).

• Ansteuern des LED-Treibers
• Messen des LED-Stroms und der LED-Spannung
• Auswerten der Licht-Information über den Verstärker
• Kommunikation mit dem Observer Mikroprozessor, um festzustellen ob dieser noch korrekt arbeitet
• Ausschalten des Signalgebers, insbesondere der Lichtsignalanlage
• Erfassen einer Umgebungstemperatur
• Eingangsstrom begrenzen
• Im Falle eines Fehlers schaltet der Master den Signalgeber, insbesondere die Lichtsignalanlage, irreversibel ab.

Tasks of the Master:

• Activation of the LED driver
• Measure the LED current and the LED voltage
• Evaluation of the light information via the amplifier
• Communication with the Observer microprocessor to see if it is still working properly
• Switching off the signal generator, in particular the traffic signal system
• Detecting an ambient temperature
• Limit input current
• In the case of a fault, the master irreversibly switches off the signal generator, in particular the traffic signal system.

• Kommunikation mit dem Master, um festzustellen ob dieser noch korrekt arbeitet
• Überprüft den Signalweg der Licht-Information hin zum Master über einen "Monitor Validation Test".
• Im Falle eines Fehlers schaltet der Observer den Signalgeber, insbesondere die Lichtsignalanlage, irreversibel ab.

Tasks of the Observer:

• Communication with the master to see if it is still working properly
• Checks the signal path of the light information to the master via a "Monitor Validation Test".
• In the event of a fault, the Observer irreversibly switches off the signal generator, in particular the traffic signal system.

In the event of a fault, both processors have the option of independently producing a short circuit via an electronic switch, which triggers an upstream fuse.

The inventive step is therefore in particular to integrate the optical monitoring of the light in the error consideration of the signal generator in addition to monitoring at least one electrical parameter and thus to achieve a higher reliability.

The advantage of this additional monitoring is in particular the increased security. The tension alone does not tell if enough light is emitted or even emitted.

The ability to adjust the brightness makes it possible to keep the signal generator running longer.

An error is in particular present if the measured actual light intensity is smaller than a predetermined light intensity threshold, in particular if the light intensity can no longer be regulated to a predetermined, larger desired light intensity.

While the invention has been further illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims (22)

1. Device (101, 501) for monitoring a signal emitter (303, 305, 307) comprising a light-emitting diode (513) for a light-signal system (301) comprising:

   - a measuring unit (103, 519; 521) in order to measure an actual light intensity (13) of the light emitted by means of the diode (513) and in order to measure at least one electrical parameter of the diode (513) and

   - a two-channel control unit (105, 505) to operate the signal emitter (303, 305, 307) as a function of the measured actual light intensity (13) and the measured electrical parameter,

   - wherein the control unit (105, 505) comprises a first processor (505) and a second processor (507),
   characterised in that

   - the first processor (505) is embodied, on the basis of the measured actual light intensity (13) and the measured electrical parameter, to actuate a driver circuit (511) of the diode (513), and

   - the second processor (507) is embodied to monitor the first processor (505) during operation for an error and, on the detection of an error, to switch off the diode (513).
2. Device (101, 501) according to claim 1, wherein each of the two processors (505, 507) is provided with its own voltage regulator (527, 529) for a respective electrical supply voltage for the two processors (505, 507).
3. Device (101, 501) according to claim 1 or 2, wherein the second processor (507) is embodied to switch the diode (513) off for a function test on the first processor (505), wherein the second processor (507) is embodied, in the absence of an error message from the first processor (505) that the diode (513) is not functioning, to prevent the diode (513) from being switched back on.
4. Device (101, 501) according to one of claims 1 to 3, wherein the first processor (505) is embodied to send a data packet to the second processor (507) and in the absence of a response packet from the second processor (507), to switch off the diode (513) and/or wherein the second processor (507) is embodied to send a data packet to the first processor (505) and in the absence of a response packet from the first processor (505) to switch off the diode (513).
5. Device (101, 501) according to one of the preceding claims, wherein the control unit (105, 505) is embodied to regulate the actual light intensity (13) to a predetermined greater desired light intensity if the measured actual light intensity (13) is below a predetermined light-intensity threshold.
6. Device (101, 501) according to claim 5, wherein the control unit (105, 505) is embodied to switch off the signal emitter (303, 305, 307) if the actual light intensity (13) cannot be regulated to the predetermined desired light intensity.
7. Device (101, 501) according to one of the preceding claims, wherein the measuring unit (103, 519; 521) comprises a light sensor and the control unit (105, 505) comprises a processing unit, which is embodied to subtract a light signal (12) measured by means of the light sensor when the diode (513) is switched off from a light signal (I1) measured by means of the light sensor when the diode (513) is switched on in order to form a subtracted light signal corresponding to the measured actual light intensity (13).
8. Device (101, 501) according to claim 7, wherein, in order to measure the light signals (12) when the diode is switched off and switched on, the control unit (105, 505) is embodied (513) to switch the diode (513) on and off periodically, wherein the period is within the millisecond range.
9. Device (101, 501) according to one of the preceding claims, wherein a temperature sensor is provided to measure a temperature of an environment of the signal emitter (303, 305, 307), wherein the control unit (105, 505) is embodied to operate the signal emitter (303, 305, 307) as a function of the measured temperature.
10. Device (101, 501) according to one of the preceding claims, wherein the measuring unit (103, 519; 521) comprises a light sensor, wherein a fibre-optic conductor is provided to conduct a part of the light emitted to the light sensor.
11. Method for monitoring a signal emitter (303, 305, 307) comprising a light-emitting diode (513) for a light-signal system (301) comprising the following steps:

    - measuring (201) an actual light intensity (13) of the light emitted by means of the diode (513) and at least one electrical parameter of the diode (513) and

    - operating (203) the signal emitter (303, 305, 307) as a function of the measured actual light intensity (13) and the measured electrical parameter,
    characterised in that

    - a driver circuit (511) of the diode (513) is actuated by means of a first processor (505) on the basis of the measured actual light intensity (13) and the measured electrical parameter, and

    - the first processor (505) is monitored during operation by means of a second processor (507) for an error, wherein, on the detection of an error, the second processor (507) switches off the diode (513).
12. Method according to claim 11, wherein a respective electrical supply voltage for the two processors (505, 507) is provided by means of its own voltage regulator (527, 529).
13. Method according to claim 11 or 12, wherein the second processor (507) switches the diode (513) off for a function test on the first processor (505) and, in the absence of an error message from the first processor (505) that the diode (513) is not functioning, prevents the diode (513) from being switched back on.
14. Method according to one of claims 11 to 13, wherein the first processor (505) sends a data packet to the second processor (507) and, in the absence of a response packet from the second processor (507), switches off the diode (513) and/or wherein the second processor (507) sends a data packet to the first processor (505) and in the absence of a response packet from the first processor (505), switches off the diode (513).
15. Method according to one of claims 11 to 14, wherein the operation includes the regulation of the actual light intensity (13) to a predetermined greater desired light intensity if the measured actual light intensity (13) is below a predetermined light-intensity threshold.
16. Method according to claim 15, wherein the signal emitter (303, 305, 307) is switched off if the actual light intensity (13) cannot be regulated to the predetermined desired light intensity.
17. Method according to one of claims 11 to 16, wherein a light sensor is used for the measuring, wherein a light signal (12) measured by means of the light sensor when the diode (513) is switched off is subtracted from a light signal (I1) measured by means of the light sensor when the diode (513) is switched on in order to form a subtracted light signal corresponding to the measured actual light intensity (13).
18. Method according to claim 17, wherein to measure the light signals (12) with a switched-off and switched-on diode (513), the diode (513) is switched on and off periodically, wherein the period is within the millisecond range.
19. Method according to one of claims 11 to 18, wherein a temperature of an environment of the signal emitter (303, 305, 307) is measured and the signal emitter (303, 305, 307) is operated as a function of the measured temperature.
20. Method according to one of claims 11 to 19, wherein a light sensor is used for the measuring and a part of the light emitted is conducted to the light sensor by means of a fibre-optic conductor.
21. Signal emitter (301) comprising:

    - a signal chamber (303, 305, 307) comprising a light-emitting diode (513) and

    - a device (101, 501) according to one of claims 1 to 10.
22. Computer program comprising a program code for carrying out the method according to one of claims 11 to 20 when the computer program is executed on a computer.

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