Laser-based weed control device with mobile power supply

Abstract

The invention relates to a laser-based weed control device having one or more weed control modules (1) which are installed on a vehicle trailer (2) and are supplied with electrical power by the vehicle trailer (2) or by a towing vehicle (3) when mobile by means of a power supply unit (4). In order to safely switch off laser units of the weed control modules (1), the power supply unit has a feed circuit (5) and a safety circuit (6) which is connected in control terms to the feed circuit (5) and contains a safety switching device (7). The laser-based weed control device allows safe, mobile use of the laser units by the carried-along power supply unit (4) for agricultural use.

Description

[0001]Laser-based weed control device with mobile power supply. The invention relates to a laser-based weed control device with one or more weed control modules installed on a vehicle trailer, which are supplied with electrical power via a power supply unit from the vehicle trailer or a towing vehicle. The laser-based weed control device enables self-sufficient, laser-based weed control in agricultural environments thanks to the mobile power supply – while complying with the safety standards stipulated for high-energy laser systems. The devices and methods for laser-based weed control are based on eradicating weeds on agricultural land through targeted irradiation with a high-energy laser beam.The laser radiation exposure leads to thermal decomposition of the plant substance and, subsequently, to its biological elimination. Since it is a chemical-free and non-invasive process, laser-based weed control is considered particularly environmentally friendly. One such weed control method is described, for example, in WO 00 / 03589 A1. To control weeds using targeted laser radiation, the method first requires identifying the weeds among the crops grown on the agricultural land. This is typically done using an image capture and image processing device, which photographically captures a section of the agricultural land and analyzes the captured image for characteristic plant characteristics. The identified plants are thus differentiated into crop plants and weeds.In the next step, the identified weed plant is targeted using a laser unit, and the irradiation or bombardment of the weed plant with a high-energy laser beam is triggered. The plants identified as crop plants or objects not identified as weeds are spared from the laser irradiation. KAUFMANN Patent and Trademark Attorneys K 43212 / 8.6 October 23, 2024. Laser-based weed control is usually carried out in an established manner using carbon dioxide lasers. Furthermore, devices for laser-based weed control based on semiconductor lasers are known, for example from EP 2848120 A1 or US 2022 / 0117218 A1. EP 2848120 A1 and US 2022 / 0117218 A1 also disclose weed control devices with a vehicle trailer driven by an agricultural tractor, on which the devices for laser-based weed control are installed.When working agricultural fields with such commercial vehicles, it is essential to supply the laser-based weed control devices with energy independently, i.e. by carrying suitable components for storing or generating the electrical energy required for laser operation. However, since the operation of high-energy lasers is associated with risks that go beyond the usual hazard potential of agricultural systems, an improved safety concept and improved safety devices are required for the agricultural use of laser-based weed control devices, in particular for the operation of the mobile power supply of the laser systems, in order to ensure sufficient operational reliability of the laser systems. The object of the invention is to provide a mobile laser-based weed control device suitable for agricultural use, which is independent, i.e.by means of electrical energy carried along or generated within the weed control device, wherein the mobile energy supply is designed to safely switch off the lasers in the event of hazardous situations associated with laser operation. This object is achieved by the laser-based weed control device according to claim 1. Expedient developments of the invention are set out in claims 2 to 10. KAUFMANN Patent and Trademark Attorneys K 43212 / 8.6 October 23, 2024 According to the invention, the laser-based weed control device comprises a vehicle trailer with one or more weed control modules installed thereon and a towing vehicle for driving the vehicle trailer. Each of the weed control modules has at least one laser unit, in particular a semiconductor laser-based one.The weed control modules are preferably designed as described in German patent application number 102023103252.6. In this regard, reference is made to German patent application number 102023103252.6, the content of which is hereby incorporated into this patent application. The weed control device according to the invention further comprises a power supply unit, which can be installed on either the towing vehicle or the vehicle trailer, and a shut-off element for the safety shutdown of the laser units of the weed control module(s). The safety shutdown is effected by a shutdown signal triggered by the shut-off element or received at the shut-off element. The shut-off element can, for example, be an emergency stop switch, or an emergency stop switch can be signal-connected to the shut-off element.In the same way, the shutdown element can be a sensor for monitoring the weed control device or a sensor for monitoring the weed control device can be signal-connected to the shutdown element. The shutdown signal is therefore triggered, for example, by the emergency stop switch or the sensor. Multiple sensors, individual sensors or switches can also be connected to the shutdown element, each of which can independently trigger the shutdown signal. The towing vehicle of the weed control device has a (conventional) on-board electrical system with an on-board voltage applied to the on-board electrical system; the on-board voltage is, for example, a 24 V DC. According to the invention, the voltage supply unit has an electrical feed circuit and an electrical safety circuit. The feed circuit has an input section, a KAUFMANN Patent- und Markenanwälte K 43212 / 8.6 23.10.2024 laser supply voltage branch and a main supply voltage branch branching off after the input section, parallel to the laser supply voltage branch. An incoming input load voltage is present at the input section of the feed-in circuit, which is fed in via a mains connection at the input of the input section. An outgoing laser supply voltage is present at the laser supply voltage branch for the electrical power supply of the laser units of the weed control module(s). This voltage is tapped off via a laser supply connection at the output of the laser supply voltage branch. Finally, an outgoing main supply voltage is present at the main supply voltage branch for the electrical power supply of the other components of the weed control device. This voltage is tapped off via a main supply connection at the output of the main supply voltage branch.According to the invention, the safety circuit of the voltage supply unit has a safety switching device, preferably a safety relay, which is connected to the on-board voltage of the towing vehicle for the voltage supply. A part of the safety circuit that is electrically connected to the shutdown element is designed as the input circuit of the safety switching device and a part of the safety circuit that is electrically connected to a start switching element of the towing vehicle is designed as the start circuit of the safety switching device. The input circuit is closed when no shutdown signal is present and open when the shutdown signal has been triggered. The input circuit is preferably designed with two channels, particularly preferably with cross-circuit detection. The start circuit is used for the manual (monitored) activation or starting of the safety switching device. The start function implemented via the start circuit for starting orto activate the safety switching device is a common function of safety switching devices. The activation or start of the safety switching device is triggered manually by actuating the start switching element of the towing vehicle. The start switching element of the towing vehicle can be a key switch, for example. KAUFMANN Patent- und Markenanwälte K 43212 / 8.6 23.10.2024 The power supply unit further comprises at least two cut-off relays, in particular exactly two cut-off relays, i.e., a first and a second cut-off relay. The cut-off relays can be integral components of the safety switching device. Each of the cut-off relays has one or more (preferably two) jointly actuated normally open contacts. The cut-off relays are integrated in the laser supply voltage branch of the feed circuit, connected in series on the normally open side, i.e., one of the normally open contacts of the first shutdown relay and one of the normally open contacts of the second shutdown relay are connected in series in a line, for example in the outer conductor of the laser supply voltage branch. Another normally open contact of the first shutdown relay and another normally open contact of the second shutdown relay can be connected in series in another line, for example in the neutral conductor of the laser supply voltage branch. According to the invention, the safety switching device controls the at least two shutdown relays in parallel, ie, the shutdown relays are controlled in the same way, so that the normally open contacts of all shutdown relays are open or closed simultaneously. When the safety switching device is activated, ie started, and when the input circuit is closed, ieIf a shutdown signal is not present, the normally open contacts of the shutdown relays release the laser supply voltage in the laser supply voltage branch, so that the laser unit(s) of the weed control module(s) are supplied with electrical energy via the laser supply connection. If the input circuit of the safety switching device is interrupted, i.e. if a shutdown signal is received, the laser supply voltage in the laser supply voltage branch is interrupted. By interrupting the supply of electrical energy to the laser unit(s) of the weed control module(s), the lasers are safely switched off. The laser-based weed control device according to the invention enables the safe, mobile use of the laser systems in agricultural use thanks to the power supply unit carried on board.The shutdown relays combined with the safety switching device according to the invention ensure the safe shutdown of the laser units in hazardous situations while simultaneously continuing to operate the other components via the main supply voltage branch of the feed circuit. KAUFMANN Patent and Trademark Attorneys K 43212 / 8.6 23.10.2024 The power supply unit can be supplied with electrical energy via a generator driven by the towing vehicle, which is connected to the mains connection of the feed circuit. The generator preferably generates alternating current, for example, with a voltage of 240 V, a frequency of 60 Hz, and a current of 90 A. Furthermore, energy storage devices such as batteries or accumulators can also be connected to the mains connection of the feed circuit. If necessary, the power supply unit can also be connected to the conventional power grid via the mains connection (wired).According to one embodiment of the laser-based weed control device, the voltage supply unit has a feedback circuit monitor and a load voltage relay containing a normally open contact. The feed circuit has a start voltage branch which branches off after the input section, parallel to the laser supply voltage branch and the main supply voltage branch, and in which the load voltage relay is integrated on the control side. The normally open contact of the load voltage relay, on the other hand, is located in the start circuit of the safety switching device; it is closed when the input load voltage is present in the feed circuit. The at least two shutdown relays also have, i.e. in addition to the normally open contacts, each an normally closed contact (operated together with the normally open contacts). The normally closed contacts of all shutdown relays are connected in series and integrated into the start circuit of the safety switching device. After activation of the safety switching device, i.e. after its start-up,The normally closed contacts of the shutdown relays are opened by activating the shutdown relays. The start circuit is therefore only closed when the input load voltage is present in the feed circuit, the safety switching device is not yet active, and the start switching element of the towing vehicle is actuated. The normally closed contacts of the shutdown relays check whether the safety switching device has assumed a safe state before being activated again. KAUFMANN Patent and Trademark Attorneys K 43212 / 8.6 October 23, 2024 According to a further embodiment of the laser-based weed control device, the power supply unit has an insulation monitor for insulation monitoring. The power supply unit also has a conventionally designed electrically conductive housing and is installed on an electrically conductive mounting element, for example, on a mounting plate.The mounting element is located on the towing vehicle or trailer, depending on the installation position of the power supply unit. The electrically conductive housing of the power supply unit can be, for example, a control cabinet. The insulation monitor has a protective conductor signal input that is electrically connected to the housing of the power supply unit, the mounting element of the weed control device, and the protective conductor terminals of the weed control module(s) via a protective conductor. The protective conductor terminals can be located, for example, on the inside and / or on the control cabinet door of the housing designed as a control cabinet or on the underside of the mounting element designed as a mounting plate.In the insulation-monitored embodiment of the laser-based weed control device, the power supply unit further comprises a monitoring relay controlled by the insulation monitor, which is preferably an integral component of the insulation monitor. The monitoring relay has one or more normally open contacts, which are integrated into the input section of the feed circuit, i.e., before the branching of the laser supply voltage branch, the main supply voltage branch, and the start voltage branch, for enabling or interrupting the input load voltage. Preferably, the monitoring relay has a normally open contact for each line (line conductor, neutral conductor) of the input section of the feed circuit, with all normally open contacts being switched together.If the insulation monitor detects that the insulation resistance falls below a minimum, the input load voltage in the input section of the feed-in circuit is interrupted, shutting down both the laser supply voltage branch and the main supply voltage branch. The insulation monitoring supplements the safe shutdown of the laser-based weed control device in the event of insulation faults. KAUFMANN Patent and Trademark Attorneys K 43212 / 8.6 23.10.2024 The combination of the power supply unit's designs with feedback circuit monitoring and insulation monitoring interacts via the load voltage relay integrated into the start-up voltage branch on the control side. If the input load voltage is interrupted by the insulation monitor, the start circuit of the safety switching device is opened. Activation or starting of the safety switching device is only possible again once the insulation faults have been rectified, i.e.when the insulation monitor is back in operation. To trigger the shutdown signal, the shutdown element can, as already explained, be connected to an emergency switch or a sensor. According to one embodiment, the vehicle trailer has a position sensor that is connected to the shutdown element. The position sensor is set up to detect the horizontal alignment of the vehicle trailer. The shutdown element, which is signal-linked to the position sensor, is designed to interrupt the input circuit of the safety switching device in the safety circuit if a predetermined target deviation from the horizontal alignment of the vehicle trailer is exceeded. The position sensor switches off the laser units of the weed control modules if the vehicle trailer is tilted beyond a predetermined level.This prevents the laser radiation, which in weed control modules is usually directed at the ground in a predetermined sector, from escaping laterally from the intended irradiation area underneath the vehicle trailer due to excessive inclination of the vehicle trailer. The position sensor system can, for example, comprise one or more inclinometers or tilt sensors. According to a preferred embodiment of the position sensor system, the vehicle trailer has an additional, spring-mounted wheel which is equipped with a pressure sensor. When the vehicle trailer is tilted, the wheel deflects or extends by a specific amount which can be detected by the pressure sensor. This embodiment of the position sensor system is particularly suitable for agricultural use due to its robustness. KAUFMANN Patent and Trademark Attorneys K 43212 / 8.6 23.10.2024 Furthermore, it can be provided that the vehicle trailer has a motion sensor system which is connected to the switch-off element. The motion sensor system is set up to detect the movement of the vehicle trailer. The switch-off element which is signal-technically connected to the motion sensor system is designed to interrupt the input circuit of the safety switching device in the safety circuit when the vehicle trailer is stationary or when the movement of the vehicle trailer is interrupted for a predefined period. This ensures that the weed control modules are essentially only active when in motion, whereas when the weed control device is stationary (for an extended period), the laser units are safely switched off. The motion sensor system can be installed, among other things, on one or more wheels of the vehicle trailer, for example in the form of tachometers or speed sensors.The vehicle trailer can have one or more laser safety curtains to shield the laser irradiation area below the installation level of the weed control modules. These are attached to the perimeter of the vehicle trailer in such a way that they enclose or surround the laser working area below the vehicle trailer. In combination with the laser safety curtain(s), the vehicle trailer can have a loss sensor connected to the shutdown element, which is configured to detect the correct position and complete presence of the laser safety curtains. The shutdown element, which is signal-linked to the loss sensor, is designed to interrupt the input circuit of the safety switching device in the safety circuit if a loss or partial loss of one of the laser safety curtains is detected by the loss sensor.The loss sensor system can, for example, include tear-off sensors attached to the attachment of the laser safety curtains to the vehicle trailer, or light barriers that monitor the presence of the laser safety curtains at specific positions. The invention is explained in more detail below using exemplary embodiments and with reference to the schematic drawings, wherein identical or similar features are provided with identical reference numerals; in this regard: KAUFMANN Patent- und Markenanwälte K 43212 / 8.6 23.10.2024 Fig. 1: the laser-based weed control device in a perspective view; Fig. 2: the feed circuit of the power supply unit in a circuit diagram; and Fig. 3: the safety circuit of the power supply unit in a circuit diagram. The laser-based weed control device intended for agricultural use according to Fig.1 comprises the vehicle trailer 2, on which five weed control modules 1 are installed, and the tractor-shaped towing vehicle 3 that drives the vehicle trailer 2. The power supply unit 4 is mounted on the rear of the towing vehicle 3. The emergency stop switch 20 is also located on the vehicle trailer 2. Furthermore, the laser safety curtains 21 are attached to the frame of the vehicle trailer 2. According to the circuit diagram of the feed-in circuit 5 shown in Fig. 2, this has the input section 5.1, the main supply voltage branch 5.2, the laser supply voltage branch 5.3, and the starting voltage branch 5.4. The feed-in circuit 5 comprises the outer conductor L1, the neutral conductor N, and the protective conductor PE. Various circuit breakers F are installed in the feed-in circuit 5 as overcurrent protection devices. The input load voltage 10 is fed into the input section 5.1 via the mains connection 9. The main switch QA2 is in the input section 5.1 is used for the manual switching on and off of the feed circuit 5 and thus of the power supply unit 4. Furthermore, the insulation monitoring in the form of the insulation monitor 8 is integrated into the input section 5.1. For the power supply, the insulation monitor 8 is connected to the outer conductor L1 via the first control supply voltage input XA1 and to the neutral conductor N via the second control supply voltage input XA2. The outer conductor L1 is also connected to the outer conductor signal input XL of the insulation monitor 8. The protective conductor signal input XPE of the insulation monitor 8 is connected to the protective conductor PE KAUFMANN Patent- und Markenanwälte K 43212 / 8.6 23.10.2024, which in turn is electrically connected to the housing of the power supply unit 4, the mounting element of the weed control device, and the protective conductor terminals of the weed control module(s) 1.During normal operation, the changeover contact of insulation monitor 8 closes and activates monitoring relay QA1, whose two make contacts are thereby closed and thus input section 5.1 is enabled. Upon detection of an insulation fault, the changeover contact of insulation monitor 8 opens and, as a result, monitoring relay QA1 opens its make contacts, which in turn interrupt input section 5.1 of supply circuit 5. After input section 5.1, main supply voltage branch 5.2 branches off in supply circuit 5, via which main supply voltage 12 is tapped at main supply connection 11. Laser supply voltage branch 5.3 also branches off after input section 5.1. Laser supply voltage 14 is provided at laser supply connection 13 via laser supply voltage branch 5.3.3, the normally open contacts of the first shutdown relay QA3 and the second shutdown relay QA4 - each separately for the phase conductor L1 and the neutral conductor N - are integrated and connected in series. The control side and the normally closed contact of the shutdown relays QA3, QA4 are components of the safety circuit 6. In the starting voltage branch 5.4 of the feed-in circuit 5, the load voltage relay QA5 is installed on the control side; the normally open contact of the load voltage relay QA5 is component of the safety circuit 6. The safety circuit 6 shown in Fig. 3 contains the safety switching device 7, which is connected to the shutdown connection 18 via the four shutdown signal inputs S11, S12, S21, S22. The connections between the KAUFMANN Patent and Trademark Attorneys K 43212 / 8.6 23.10.2024 shutdown signal inputs S11, S12, S21, S22 and the shutdown connection 18 form the input circuit of the safety switching device 7.The safety switching device 7 is connected to the on-board electrical system voltage 16 of the towing vehicle 3 via the two operating voltage inputs A1, A2; the on-board electrical system voltage 16 is fed into the safety circuit 6 via the towing vehicle connection 15. Furthermore, the start signal 17, which is triggered by the start switching element in the form of a key switch in the towing vehicle 3, is received via the towing vehicle connection 15. To form the start circuit of the safety switching device 7, the start signal lines of the safety circuit 6 leading from the towing vehicle connection 15 are connected on the one hand to the start signal input S34 of the safety switching device 7 and on the other hand, via the series connection of the break contact of the load voltage relay QA5, the make contact of the first cut-off relay QA3 and the make contact of the second cut-off relay QA4 to the second cut-off signal input S12 of the safety switching device 7. In the initial state, which exists when the safety switching device 7 is not yet activated orhas been started, the normally open contacts in the safety switching device 7 are open. To start the safety switching device 7, the input circuit must be closed, the input load voltage 10 must be present in the feed circuit 5 so that the normally open contact of the load voltage relay QA5 is closed, and the start signal must be triggered via the start switching element / key switch of the towing vehicle 3. This starts the safety switching device 7, whereby its normally open contacts are closed. By closing the normally open contacts of the safety switching device 7, the two shutdown relays QA3, QA4 are controlled simultaneously, whereby their normally open contacts close the laser supply voltage branch 5.3 of the feed circuit 5 and their normally closed contacts open the start circuit of the safety switching device 7.If the shutdown signal 19 is received via the shutdown connection 18, the input circuit of the safety switching device 7 is interrupted, the normally open contacts in the safety switching device 7 open and interrupt the laser supply voltage branch 5.3 of the feed circuit 5 by controlling the KAUFMANN Patent and Trademark Attorneys K 43212 / 8.6 23.10.2024 shutdown relays QA3, QA4. The safety switching device 7 can be switched on again manually via the start switching element, ie the key switch, in the towing vehicle 3, after the causes that triggered the shutdown signal 19 have been eliminated and the shutdown signal 19 has been deactivated. KAUFMANN Patent and Trademark Attorneys K 43212 / 8.6 October 23, 2024 List of reference symbols 1 Weed control module 2 Vehicle trailer 3 Towing vehicle 4 Voltage supply unit 5 Feed circuit 5.1 Input section 5.2 Main supply voltage branch 5.3 Laser supply voltage branch 5.4 Starting voltage branch 6 Safety circuit 7 Safety switching device 8 Insulation monitor 9 Mains connection 10 Input load voltage 11 Main supply connection 12 Main supply voltage 13 Laser supply connection 14 Laser supply voltage 15 Towing vehicle connection 16 On-board network voltage 17 Start signal 18 Shutdown connection 19 Shutdown signal 20 Emergency stop switch 21 Laser safety curtain A1 First operating voltage input of the safety switching device A2 Second operating voltage input of the safety switching device F Circuit breaker L1 Outer conductor (current-carrying conductor) N Neutral conductor PE Protective conductor QA1 Monitor relay KAUFMANN Patent and Trademark Attorneys K 43212 / 8.6 23.10.2024 QA2 Main switch of the feed circuit QA3 First shutdown relay QA4 Second shutdown relay QA5 Load voltage relay S11 First shutdown signal input of the safety switching device S12 Second shutdown signal input of the safety switching device S22 Third shutdown signal input of the safety switching device S23 Fourth shutdown signal input of the safety switching device S34 Start signal input of the safety switching device XA1 First control supply voltage input of the insulation monitor XA2 Second control supply voltage input of the insulation monitor XL Outer conductor signal input of the insulation monitor XPE Protective conductor signal input of the insulation monitor KAUFMANN Patent and Trademark Attorneys K 43212 / 8.6 October 23, 2024.

Claims

AMENDED CLAIMS received by the International Bureau on 18 March 2025 (18.03.2025) 1 . Laser-based weed control device comprising: a vehicle trailer (2) with at least one weed control module (1) installed thereon for laser-based weed control, wherein the weed control module (1) has at least one laser unit, a towing vehicle (3) for driving the vehicle trailer (2), wherein the towing vehicle (3) has an on-board network with an on-board network voltage (16) present in the on-board network, a voltage supply unit (4), and at least one shutdown element for the safety shutdown of the laser unit of the weed control module (1), characterized in that the voltage supply unit (4) has an electrical feed circuit (5) and an electrical safety circuit (6), wherein the feed circuit (5) has an input section (5.1), at which an incoming Input load voltage (10), a laser supply voltage branch (5.3) branching off after the input section (5.1), to which an outgoing laser supply voltage (14) for supplying the electrical power to the laser unit of the weed control module (1) is applied, and a main supply voltage branch (5.2) branching off after the input section (5.1), parallel to the laser supply voltage branch (5.3), to which an outgoing main supply voltage (12) for supplying the electrical power to the other components of the weed control device is applied, the safety circuit (6) has a safety switching device (7) which is connected to the on-board network voltage (16) of the towing vehicle (3) for supplying the voltage, a part of the Safety circuit (6) as the input circuit of the safety switching device (7) and a part of the safety circuit (6) which is electrically connected to a start switching element of the towing vehicle (3) is designed as the start circuit of the safety switching device (7) for activating the safety switching device (7), the voltage supply unit (4) has at least two cut-off relays (QA3, QA4), each of the cut-off relays (QA3, QA4) having a make contact, and the Shutdown relays (QA3, QA4) are integrated in the laser supply voltage branch (5.3) of the feed circuit (5) and are connected in series on the normally open side, the safety switching device (7) controls at least two shutdown relays (QA3, QA4) in parallel, whereby when the safety switching device (7) is activated, the normally open contacts of the shutdown relays (QA3, QA4) release the laser supply voltage (14) in the laser supply voltage branch (5.3) when the input circuit of the safety switching device (7) is closed, and when the input circuit of the safety switching device (7) is interrupted, the laser supply voltage (14) in the laser supply voltage branch (5.3), and the power supply unit (4) comprises an electrically conductive housing which is installed on an electrically conductive mounting element of the weed control device, the power supply unit (4) has an insulation monitor (8) for insulation monitoring, which has a protective conductor signal input (XPE) which is electrically conductively connected to the housing of the power supply unit (4), the mounting element of the weed control device and protective conductor connections of the weed control module (1) by means of a protective conductor (PE), and the power supply unit (4) has a monitor relay (QA1) which is controlled by the insulation monitor (8) and contains one or more make contacts, wherein the make contact(s) of the monitor relay (QA1) for enabling or interrupting the input load voltage (10) are integrated in the input section (5.1) of the feed circuit (5).

2. Laser-based weed control device according to claim 1, characterized in that the voltage supply unit (4) has a feedback circuit monitoring and a load voltage relay (QA5) containing a normally open contact, wherein the feed circuit (5) has a feed-in circuit branching off after the input section (5.1), parallel to the laser supply voltage branch (5.3) and to the main supply voltage branch (5.2). Starting voltage branch (5.4) in which the load voltage relay (QA5) is integrated on the control side, when the input load voltage (10) is present, which is fed into the starting circuit of the The normally open contact of the load voltage relay (QA5) integrated in the safety switching device (7) is closed, the at least two cut-off relays (QA3, QA4) each further comprise an open contact, the open contacts of all cut-off relays (QA3, QA4) being connected in series and integrated into the start circuit of the safety switching device (7), and the safety switching device (7) opens the open contacts in the start circuit of the safety switching device (7) after it has been activated by controlling the cut-off relays (QA3, QA4).

3. Laser-based weed control device according to claim 1 or 2, characterized in that the weed control device has a generator for generating electrical energy, which generator is driven by the towing vehicle (3) and is connected to a mains connection (9) of the voltage supply unit (4).

4. Laser-based weed control device according to one of claims 1 to 3, characterized in that the input circuit of the safety switching device (7) in the safety circuit (6) is designed as a two-channel device with cross-circuit detection.

5. Laser-based weed control device according to one of claims 1 to 4, characterized in that the start switching element of the towing vehicle (3) is a key switch.

6. Laser-based weed control device according to one of claims 1 to 5, characterized in that the shutdown element is an emergency stop switch (20) for interrupting the input circuit of the safety switching device (7) or an emergency stop switch (20) is connected to the shutdown element for interrupting the input circuit of the safety switching device (7).

7. Laser-based weed control device according to one of claims 1 to 6, characterized in that the vehicle trailer (2) has a position sensor which is connected to the switch-off element, wherein the position sensor system is designed to detect the horizontal orientation of the vehicle trailer (2), and wherein the switch-off element is designed to interrupt the input circuit of the safety switching device (7) in the safety circuit (6) if a predetermined target deviation from the horizontal orientation of the vehicle trailer (2) is exceeded.

8. Laser-based weed control device according to one of claims 1 to 7, characterized in that the vehicle trailer (2) has a movement sensor system which is connected to the switch-off element, wherein the movement sensor system is set up to detect the movement of the vehicle trailer (2), and wherein the switch-off element is set up to interrupt the input circuit of the safety switching device (7) in the safety circuit (6) when the vehicle trailer (2) is stationary or when the movement of the vehicle trailer (2) is interrupted for a predefined period.

9. Laser-based weed control device according to one of claims 1 to 8, characterized in that one or more laser protection curtains (21) are attached to the vehicle trailer (2), wherein the vehicle trailer (2) has a loss sensor system connected to the switch-off element, which is designed to detect the correct and complete presence of the laser protection curtains (21), and wherein the switch-off element is designed to switch off the laser protection curtains (21) in the event of a loss or partial loss of one of the Laser safety curtains (21) to interrupt the input circuit of the safety switching device (7) in the safety circuit (6). Declaration pursuant to Article 19 (1) PCI Claim 1 was specified in such a way that an insulation monitor is integrated into the power supply unit. The amendment is based on the original claim 3; there is no impact on the description and drawings.

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