Control circuit for pulsed control of a light-emitting means
The invention relates to a control circuit ( 50 ) for pulsed control of a light-emitting means ( 52 ), in particular an LED or a laser diode ( 52 ), having a switched-mode power supply unit ( 54 ) with a first switch ( 64 ) arranged in a primary circuit of the switched-mode power supply unit ( 54 ), wherein the switched-mode power supply unit ( 54 ) has a primary-side connector ( 62 ) for connection to a supply voltage, a secondary-side connector ( 67 ) for supplying the light-emitting means ( 52 ) and a switching input ( 65 ) for operating the first switch ( 64 ), having a storage capacitor ( 68 ) arranged between the secondary-side connector ( 67 ) and a ground ( 66 ), having a second switch ( 70 ) arranged in a current path ( 71 ) in parallel with the storage capacitor ( 68 ), wherein the light-emitting means ( 52 ) is positionable in the current path ( 71 ), and having a control unit ( 72 ) to control the first and the second switch ( 64, 70 ), wherein the control unit ( 72 ) is designed to operate the first switch ( 64 ) in order to induce at least one charge pulse for charging the storage capacitor ( 68 ) in the secondary circuit and to operate the second switch ( 70 ) in order to discharge the storage capacitor ( 68 ) while generating a light pulse ( 82 ) via the light-emitting means ( 52 ). The invention also relates to a LiDAR-based environmental sensor, in particular a laser scanner, for use in a vehicle, having an abovementioned control circuit ( 50 ) and a laser diode ( 52 ). The invention further relates to a method for the pulsed control of a light-emitting means ( 52 ), in particular an LED or a laser diode ( 52 ), comprising the steps of providing a storage capacitor ( 68 ) and a current path ( 71 ) that is parallel thereto and in which the light-emitting means ( 52 ) is arranged, of generating at least one charge pulse for charging the storage capacitor ( 68 ), and of discharging the storage capacitor ( 68 ) via the light-emitting means ( 52 ) while generating a light pulse ( 82 ).
1. A control circuit for pulsed control of a light-emitting means, the control circuit comprising:
a switched-mode power supply unit with a first switch arranged in a primary circuit of the switched-mode power supply unit, wherein the switched-mode power supply unit has a primary-side connector for connection to a supply voltage, a secondary-side connector for supplying the light-emitting means and a switching input for operating the first switch;
a storage capacitor arranged between the secondary-side connector and a ground;
a second switch arranged in a current path in parallel with the storage capacitor, wherein the light-emitting means is positionable in the current path; and
a control unit to control the first and the second switch,
wherein the control unit is configured to operate the first switch in order to induce at least one charge pulse for charging the storage capacitor in a secondary circuit and to operate the second switch in order to discharge the storage capacitor while generating a light pulse via the light-emitting means, and
wherein the control unit is configured to coordinate operation of the first and second switches such that, at no time, the first switch and the second switch are simultaneously closed.
2. The control circuit according to claim 1 , wherein
the control circuit has a diode that is arranged at the secondary-side connector of the switched-mode power supply unit and blocks a reverse current from the storage capacitor into the switched-mode power supply unit.
3. The control circuit according to claim 1 , wherein the control unit is configured to operate the first switch and the second switch such that the charge pulses and the light pulses are generated with a temporal offset.
4. The control circuit according to claim 1 , wherein the control circuit is configured to operate the first switch so as to charge the storage capacitor with charge pulses until a specified capacitor voltage is reached.
5. The control circuit according to claim 4 , wherein the control unit is configured to charge the storage capacitor with a specified number of charge pulses.
6. The control circuit according to claim 5 , wherein the control unit is configured to charge the storage capacitor with the specified number of charge pulses directly before the discharge of the storage capacitor via the light-emitting means.
7. The control circuit according to claim 4 , wherein the control circuit has a measurement apparatus for measuring a voltage across the storage capacitor.
8. The control circuit according to claim 1 , wherein the control unit is implemented as an FPGA.
9. The control circuit according to claim 1 , wherein the second switch is implemented as a field effect transistor.
10. A LiDAR-based environmental sensor for use in a vehicle, comprising: a control circuit according to claim 1 ; and a laser diode.
11. The control circuit of claim 1 , wherein the light-emitting means is one of a LED and a laser diode.