LED DRIVER CIRCUIT
First Claim
1. A circuit for operating at least one LED, comprising:
- a driver circuit with a coil and with a switch which is connected in series with the coil and clocked at a high frequency,wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED,wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal to a control unit which ascertains the temporally averaged value of the current through the LED on the basis of the value of the registering signal at the end of the on-time cycle and also on the basis of the value at the end of the demagnetizing phase.
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Accused Products
Abstract
An emergency-lighting device for operating a light-source, in particular an LED, comprises an energy storage unit, a charging circuit, to be supplied with a mains supply voltage (Uin), for charging the energy storage unit during charging operation, the charging circuit comprising a potential separation, and also a driver circuit, supplied by the energy storage unit during emergency-light operation, for operating the light-source. Furthermore a control unit is provided which is designed for monitoring the state of the mains supply voltage (Uin) during charging operation and, when an emergency condition is detected, for activating emergency-light operation, the control unit ascertaining the state of the mains supply voltage (Uin) on the basis of operating variables of the emergency-lighting device which are measured on the output side of the charging circuit.
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Citations
29 Claims
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1. A circuit for operating at least one LED, comprising:
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a driver circuit with a coil and with a switch which is connected in series with the coil and clocked at a high frequency, wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED, wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal to a control unit which ascertains the temporally averaged value of the current through the LED on the basis of the value of the registering signal at the end of the on-time cycle and also on the basis of the value at the end of the demagnetizing phase. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 25)
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19. A circuit for operating at least one LED, comprising:
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a driver circuit with a coil and with a switch which is connected in series with the coil and clocked at a high frequency, wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED, wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal to a control unit, further comprising a unit for registering the battery-discharge current which is functionally connected to the control unit, wherein for the purpose of regulating the battery-discharge current the current through the LED is adjustable, in a manner depending on the registered battery-discharge current, by adjustment of the switching behavior of the switch of the driver circuit.
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20. A circuit for operating at least one LED, comprising:
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a driver circuit with a coil and with a switch which is connected in series with the coil and clocked at a high frequency, wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED, wherein in the demagnetizing-current path when the switch is open a current-registering means is provided, further comprising a circuit for registering the battery voltage, wherein the current through the LED is adjustable, in a manner depending on an output signal of the circuit for registering the battery voltage, by adjustment of the switching behavior of the switch of the driver circuit.
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21. A circuit for operating at least one LED, comprising:
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a driver circuit with a coil and with a switch connected in series with the coil and clocked at a high frequency, wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED, wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal to a control unit, the control unit carrying out a test measurement of electrical parameters at start-up, in order to determine whether an LED or which LED is connected to the driver circuit. - View Dependent Claims (22, 23)
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24. A circuit for operating at least one LED, comprising:
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a driver circuit with a coil and with a switch which is connected in series with the coil and clocked at a high frequency, wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED, wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal to a control unit, the control unit increasing the LED current at start-up, by appropriate triggering of the switch of the driver circuit, from a low value to a stationary operating value.
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26. A process for ascertaining the current through an LED which is operated by a circuit that comprises:
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a coil and a switch connected in series with the coil, wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED, wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal, wherein the temporally averaged value of the current through the LED is ascertained on the basis of the value of the registering signal at the end of the on-time cycle and also on the basis of the value at the end of the demagnetizing phase.
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27. A process for operating an LED with a circuit that comprises:
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a coil and a switch which is connected in series with the coil, wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED, wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal, wherein the LED is operated from a battery, wherein the battery-discharge current is registered and for the purpose of regulating the battery-discharge current the current through the LED is adjusted, in a manner depending on the registered battery-discharge current, by adjustment of the switching behavior of the switch of the driver circuit.
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28. A process for operating an LED with a circuit that comprises:
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a coil and a switch which is connected in series with the coil, wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED, wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal, wherein the LED is operated from a battery, wherein the battery voltage is registered and the current through the LED is adjusted, in a manner depending on an output signal of the circuit for registering the battery voltage, by adjustment of the switching behavior of the switch of the driver circuit.
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29. A process for operating an LED with a circuit that comprises:
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a coil and a switch which is connected in series with the coil, wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED, wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal, wherein the LED voltage is increased at start-up of the circuit, by appropriate triggering of the switch of the driver circuit, from a low value to a stationary operating value.
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Specification