Device and method for coagulation and dissection of biological tissue

Abstract

The invention relates to a device (20) and a method for coagulating and / or dissecting biological tissue. The device (20) comprises a device (21) and an instrument (26) electrically connected to the device (21). On the instrument (26), at least a first switch (32) is provided for manual operation, which is part of an operating circuit (45). An evaluation circuit (40) of the device (21) provides an evaluation signal (S) for the instrument (26). In addition, the device (21) can generate a supply voltage (UV) or alternatively a supply current (IV) and provide it to the instrument (26). Under initial conditions, the evaluation signal (S) comprises only one polarity. The evaluation signal (S) is provided to a control circuit (70) of the instrument (26), wherein the characteristics of the evaluation signal (S) are adjusted according to the operating conditions of the first switch (32). The evaluation circuit (40) of the device (21) detects the characteristics and can initiate the output of the supply voltage (UV) and can change the polarity (S1, S2) of the evaluation signal (S) according to the requested cutting mode. In the cutting mode, the evaluation signal (S) at least temporarily also comprises a second polarity (S2).

Description

Technical Field

[0001] The present invention relates to an apparatus and a method for coagulating and dissecting biological tissues. The apparatus comprises an instrument and a device for supplying electric energy to the instrument. Background Art

[0002] Such a device is known, for example, from EP 3132765A1. The instrument has a tool with a cutting electrode and a plurality of coagulation electrodes. The electrodes can be supplied with electrical energy by means of an operating circuit. To this end, the operating circuit comprises a transformer, which is connected to the cutting electrode via a power switch on its secondary side. The instrument has a cutting activation switch and a coagulation activation switch. The coagulation activation switch is mechanically coupled to the power switch. During operation of the coagulation activation switch, the electrical connection between the cutting electrode and the transformer is interrupted or switched so that no cutting voltage is applied to the cutting electrode.

[0003] WO 2019 / 126370 A1 describes a device and a method for coagulating and cutting biological tissue. The device has a device having a sealing stage and a cutting stage for supplying power to a connected instrument with a coagulation voltage for sealing or a cutting voltage for cutting. The two stages each include a converter for voltage control and can be operated independently of each other. For cutting, a sealing voltage is first provided at a first time interval, and a cutting voltage is subsequently provided at a second time interval.

[0004] Instruments for coagulation and cutting can be disposable or reusable instruments. Especially for disposable instruments, manufacturing costs play an important role. Safe operation must be guaranteed.

[0005] It may therefore be seen as an object of the present invention to provide an instrument which can be operated in a simple and safe manner and which can be manufactured inexpensively. Summary of the invention

[0006] This object is solved by the device and method claimed in the present invention.

[0007] The device of the invention comprises a device and an instrument electrically connected to the device. With the aid of the instrument, biological tissue can be sealed (coagulated) and / or cut (dissected). For this purpose, the instrument comprises corresponding electrodes.

[0008] The device is configured to provide a supply voltage or a supply current for an instrument at a device output. In addition, the device comprises an evaluation circuit configured to provide an evaluation signal for an instrument at a second device output.

[0009] The apparatus has an operating circuit having a supply connector for connection to a first device output and having a signal connector for connection to a second device output. A control circuit is electrically connected to the signal connector and is configured to generate a control signal depending on the polarity of an evaluation signal provided by the device. In addition, the control circuit has a first switch that can be manually operated. According to this example, the first switch is used to activate a cutting mode of the apparatus.

[0010] In addition, the operating circuit of the instrument comprises a switching unit which can be controlled by means of a control signal. The switching unit can adopt a first switching condition or a second switching condition. The switching unit is directly or indirectly connected to the supply connector and directly or indirectly connected to the cutting output. Depending on the polarity of the evaluation signal, a control signal is generated which causes the switching unit to adopt the first switching condition or the second switching condition.

[0011] In a preferred embodiment, the switch unit can be arranged in series between the supply connector and the cutting output. In this configuration, for example, the switch unit can switch between a first switching condition of conduction and a second switching condition of blocking. Alternatively, the switch unit can also include a first switching condition of conduction and a second switching condition of conduction, wherein, depending on the switching condition, the coagulation voltage or the cutting voltage is applied to the cutting output depending on whether the instrument or device should be operated in a coagulation mode or a cutting mode.

[0012] In a first switching condition of the switching unit, an electric cutting voltage or an electric cutting current suitable for cutting biological tissue is provided at the cutting output. In contrast, in a second switching condition, there is no electric cutting voltage or electric cutting current sufficient for cutting biological tissue at the cutting output. In the second switching condition, an electric voltage or current substantially equal to zero may be provided at the cutting output, or alternatively a voltage or current insufficient for cutting but suitable for coagulation, for example, may be provided at the cutting output.

[0013] The control circuit is configured to adjust or modify a characteristic of the evaluation signal according to the operating condition of the first switch. For example, the characteristic of the evaluation signal may be an amount, an amplitude, an average value, etc. The characteristic is preferably independent of the polarity of the evaluation signal. In a preferred embodiment, the amount of the evaluation current flowing through the control circuit may be used as a characteristic, for example, to characterize whether the first switch is operating or not operating.

[0014] The device of the apparatus is further configured to detect a characteristic of the evaluation signal, for example, the amount of the evaluation current affected or regulated by the control circuit. Thereby, the device can determine whether the first switch for activating the cutting mode is operated or not operated. Depending on the detected characteristic of the evaluation signal, the polarity of the evaluation signal is further regulated by the evaluation circuit.

[0015] Due to the polarity of the evaluation signal, the condition of the control signal is in turn defined and, if necessary, changed. Thus, a control signal can be generated based on the polarity of the evaluation signal and, in doing so, the switching unit can be caused to assume a first or second switching condition such that the device operates in the desired coagulation mode or cutting mode.

[0016] The signal processing by means of the control circuit and the evaluation circuit is very simple and can be realized inexpensively. Complex mechanical devices for coupling the switching unit and the control circuit can be omitted. The control is carried out electrically and / or optically via the control signal. The device can be constructed in a simple manner using standard components.

[0017] In an embodiment, the switch unit may include or may be formed by one or more semiconductor switches. At least a mechanical switch may be omitted from the switch unit. This in turn avoids the generation of sparks or arcs when changing the switching conditions.

[0018] The instrument of the device can be a disposable instrument or a reusable instrument. In both cases, the instrument can be simply configured and therefore has low manufacturing costs.

[0019] If the evaluation signal conditioned by the control circuit indicates that the first switch is operated, the evaluation signal may include different polarity conditions during different phases. Preferably, in a cutting mode with an operated first switch, during a first phase starting with the operation of the first switch, the evaluation signal exclusively has the first polarity. In particular, the amount of the evaluation signal may be constant during the first phase.

[0020] The first phase may be followed by a second phase, wherein the evaluation signal alternatively or alternately comprises a first polarity and a second polarity opposite to the first polarity. For example, the first polarity may be negative and the second polarity may be positive, or vice versa.

[0021] For example, the evaluation signal may be a current or a voltage. For example, during the first phase, a direct current or a direct voltage may be provided as the evaluation signal, and during the second phase, an alternating voltage or an alternating current may be provided as the evaluation signal. The signal shape during the second phase may vary and may be, for example, a square wave signal, a triangular signal or a sinusoidal signal. During the second phase, the evaluation signal may have a positive half-wave and a negative half-wave, which may include equal duration or different durations and / or equal amplitude or different amplitudes.

[0022] During the second phase, the signal portion of the evaluation signal having the first polarity can be used to evaluate the operating condition of the first switch and the signal portion having the second polarity can be used to keep the switching unit in a desired switching condition by means of the control signal.

[0023] In particular, if the evaluation signal at least temporarily comprises the second polarity during the second phase, the control circuit is configured to switch the switching unit by means of the control signal under a first switching condition in which an electrical cutting voltage is applied or an electrical cutting current is provided at the cutting output.

[0024] If the evaluation signal comprises only the first polarity during the first phase, the switching unit is caused to assume the second switching condition by means of the control signal. If the evaluation signal comprises the first polarity, the control signal can be substantially zero. In the second switching condition, no voltage or current is available at the cutting output that can implement cutting of biological tissue.

[0025] In a preferred embodiment, the device may include a controllable energy source (current source or voltage source) to provide a supply voltage or a supply current at the first device output. The evaluation circuit of the device may be configured to control the energy source by means of an activation signal. For example, the supply voltage or the supply current may be switched on or off by means of an activation signal.

[0026] Advantageously, the control circuit comprises a manually operable second switch in addition to the first switch. The second switch can be used to activate the coagulation mode. In an embodiment of the invention, the two switches can be configured so that they can be operated independently of each other, i.e., individually or also simultaneously. As an alternative to this, the two switches can also be mechanically coupled so that only one of the two switches can be operated at a time, for example in the case of a rocker switch.

[0027] In a preferred embodiment, the first switch and the second switch are configured as buttons, respectively. For example, the button can take a blocking condition in its initial condition and can be manually switched in a conducting condition.

[0028] Advantageously, the control circuit is configured to adjust the characteristics of the evaluation signal depending on the operating conditions of the second switch. For example, the amount of the evaluation signal can vary depending on whether no switch or only the first switch or only the second switch or both switches are operated. Depending on which switch operation is detected in the evaluation circuit of the device based on the characteristics of the evaluation signal, its polarity is adjusted. In an embodiment, the cutting mode with phases of alternating polarity of the evaluation signal is only activated if exclusively the first switch has been operated. In all other cases, the evaluation signal can exclusively have the first polarity.

[0029] It is also advantageous if the evaluation circuit is configured to generate an activation signal for switching on or providing a supply voltage or a supply current at the first device output, if it has been detected based on the properties of the evaluation signal that one of the two switches has been operated.

[0030] In one embodiment, the instrument may have at least one cutting electrode, at least one first coagulation electrode, and at least one second coagulation electrode. For example, the cutting output may be connected to the at least one cutting electrode. The first coagulation output of the operating circuit may be connected to the at least one first coagulation electrode. The second coagulation output of the operating circuit may be connected to the at least one second coagulation electrode.

[0031] In a preferred embodiment, the control circuit comprises a control element configured to generate the control signal.

[0032] Advantageously, the operating circuit comprises a coupling device comprising a transmitter component and a receiver component galvanically separated from the transmitter component. By means of the transmitter component, control signals can be transmitted from the control circuit to a receiver component which is connected to the switching unit or is part of the switching unit.

[0033] In an embodiment, the transmitter component is a control element. In doing so, the receiver component may be connected to a control port of a controllable semiconductor switch of the switching unit.

[0034] For example, at least one light emitting diode may be used as the transmitter component and at least one photodiode may be used as the receiver component. For example, the transmitter component and the receiver component may be arranged as a common unit in a common housing. For example, the unit may be an optical coupler.

[0035] Advantageously, the receiver component is connected to the control port of the switch unit via a loading and unloading circuit. In case of a cutting request (e.g. operation of the first switch), it is also possible to maintain the first switching condition of the switch unit by means of the loading and unloading circuit during the duration of application of the first half-wave. Preferably, if no voltage is to be applied to the cutting electrode suitable for cutting, the loading and unloading circuit is further configured to dissipate the charge in the at least one control port of the switch unit so as to allow switching of the switch unit in the second switching condition.

[0036] In an embodiment, the switching unit may be configured without a mechanical switch and may exclusively include semiconductor switches, such as bipolar transistors and / or field effect transistors and / or IGBTs.

[0037] Advantageously, the first switch and the control element are connected in series in the first circuit branch. The first circuit branch can be connected to the signal connector. In doing so, when the first switch is disconnected, the current flowing through the control element can be suppressed.

[0038] For example, in the first circuit branch, a unidirectional current path can be provided, in which the control element is arranged. In this unidirectional current path, if the second half-wave of the evaluation signal is applied, the current is allowed to flow only in one direction, in particular in the current flow direction. For this purpose, at least one component with a diode function is present in the unidirectional current path. The component with a diode function can be, for example, the control element itself. Alternatively or additionally, another component with a diode function can be provided in the unidirectional current path, in the simplest case a diode. As an alternative to a diode, it is also possible to use controlled semiconductor switches, which only assume their conductive condition during the second half-wave of the evaluation signal.

[0039] In an embodiment, the control element is configured as a light emitting diode.In addition to the light emitting diode, a separate diode may be connected in series to the control element, preferably upstream in the direction of current flow.

[0040] Advantageously, a further parallel current path is provided in the first circuit branch parallel to the unidirectional current path, wherein for example a resistor can be arranged in the parallel current path. If a resistor is mentioned in the present application, this is meant to be an ohmic resistor, as long as the indication is to the contrary. The first switch is preferably connected in series to the unidirectional current path and the parallel current path.

[0041] In addition, it is advantageous if the second switch is arranged in a second circuit branch of the control circuit. The second circuit branch is connected to the signal connector. Preferably, a resistor is connected in series to the second switch.

[0042] In an embodiment, the second switch and the control element are coupled via a connecting current path. For example, the connecting current path can establish a permanent electrical connection between the second switch and the control element that cannot be disconnected. The connecting current path can be configured without components. In particular, the second switch and the connecting current path are connected in parallel to the control element and the first switch. If the second switch is closed or turned on, a low-resistance bypass of the control element is achieved. Therefore, if the second switch is turned on, no current flow through the control element occurs. A low-resistance bypass of the control element refers to a bypass having such a low resistance value that the voltage at the bypass is substantially equal to zero and is particularly less than the activation voltage of the control element, such as the forward voltage of a light-emitting diode.

[0043] It is also advantageous if the first coagulation output of the operating circuit is connected to the supply connector without a switch. For example, a capacitor may be arranged in such a connection.

[0044] Preferably, the operating circuit comprises a transformer circuit having a transformer. The transformer circuit is connected on its primary side to the supply connector and on its secondary side to the cutting output, wherein these connections may be direct or indirect connections. The transformer of the transformer circuit may be configured as an autotransformer without galvanic separation. Alternatively, the transformer may also have a primary side that is galvanically separated from the secondary side. The transformer circuit is particularly configured to increase the supply voltage applied at the supply connector, for example an AC voltage from about 100 volts to about 450 volts.

[0045] In the embodiments explained above, the operating circuit is part of the instrument and can be arranged in the housing of the instrument. For example, the operating circuit or its parts can be arranged in addition to or instead of the arrangement in the housing of the instrument, or can be arranged in a separate module, which can be electrically connected to the instrument and can be electrically connected between the device and the instrument. For example, the module can be a plug module, which can be releasably connected to the device and the instrument electrically and / or mechanically. It can also be arranged on the connecting wire or cable of the instrument.

[0046] Another independent aspect of the present invention is characterized by an electrosurgical instrument, which is configured to seal biological tissue in a coagulation mode and cut biological tissue in a cutting mode. The instrument has an electronically and / or optically controlled switch unit, which includes at least one semiconductor switch. The switch unit can provide electrical parameters (cutting voltage and / or cutting current) suitable for cutting biological tissue at a cutting electrode under a first switching condition. On the contrary, under a second switching condition of the switch unit sufficient for cutting biological tissue, no electrical cutting voltage or electrical cutting current is available at the cutting electrode. In the cutting mode, the control of the switch unit causes the switch unit to take the second switching condition at least during a stage and preferably before cutting. In the coagulation mode, the switch unit is continuously maintained under the second switching condition. The electrical and / or optical control signal for controlling the switch unit can be generated by the instrument, for example based on the evaluation signal explained above and / or another signal and / or the condition of the power supply device of the instrument connected to the instrument, and the evaluation signal and / or another signal and / or the condition of the power supply device of the instrument connected to the instrument can be detected by the instrument, or as an alternative also independent of the device.

[0047] This further aspect may be combined with one or more features of the device explained above, and in particular with the configuration of the above-described apparatus according to the first explained aspect of the invention.

[0048] A method of operating a device for coagulating and cutting biological tissue, in particular by using one of the embodiments explained above, comprises the following steps:

[0049] Firstly, an evaluation signal is generated and provided at a second device output of the instrument, and in particular at the control circuit at the second device output. Preferably, the evaluation signal comprises only the first polarity in an initial condition.

[0050] An evaluation signal is received at the signal connector. Depending on the operating conditions of the first switch and the optionally provided second switch, a characteristic of the evaluation signal changes, which characteristic can be detected by the evaluation circuit. The characteristic of the evaluation signal detected by the evaluation circuit can be, for example, the amount of an evaluation current flowing through the control circuit due to the evaluation signal. The characteristic indicates whether the first switch or the optionally provided second switch has been operated, and therefore whether the device should be operated in a cutting mode (e.g., the first switch is operated) or in a coagulation mode (e.g., the second switch is operated). The polarity of the evaluation signal is adjusted depending on the detected characteristic of the evaluation signal and therefore depending on the operating conditions of the at least one switch.

[0051] Based on the polarity of the adjusted evaluation signal, a control signal is then generated for the switching unit, so that it assumes the first switching condition or the second switching condition. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Advantageous configurations of the invention are derived from the dependent claims, the description and the drawings. Subsequently, preferred embodiments of the invention are explained in detail with reference to the drawings. The drawings show:

[0053] Figure 1 is a schematic diagram of an apparatus for coagulation and cutting, the apparatus having a device and an instrument electrically connected to the device,

[0054] Figure 2 yes Figure 1 A partial perspective view of the instrument tool,

[0055] Figure 3 is a circuit diagram of an embodiment of the operating circuit of the instrument,

[0056] FIG4 is a schematic diagram of the time course of an exemplary evaluation signal,

[0057] FIG5 is a schematic diagram of the time course of the coagulation voltage in the cutting mode of the device,

[0058] Figure 6 is a schematic diagram of the time course of the cutting voltage in the cutting mode of the device,

[0059] Figure 7-12 yes Figure 3 Circuit diagram of an embodiment of the operation circuit of the control circuit under different conditions,

[0060] Fig.13 is used for Figure 3 Circuit diagram of an optional voltage increasing circuit for supply voltage,

[0061] Fig.14 is used for Figure 3 A circuit diagram of a modified embodiment of the operating circuit of the switch unit, and

[0062] Fig.15 is a modified embodiment of a circuit portion of a control circuit for realizing the diode function by means of a transistor. DETAILED DESCRIPTION

[0063] Figure 1 An apparatus 20 for coagulation and cutting is shown. The apparatus 20 has a device 21 which provides a supply voltage UV or a supply current IV at a first device output 22. To this end, the device comprises an RF current source or an RF voltage source 42 which is preferably controllable by means of an activation signal W, or at least can be switched on and off. An evaluation signal S is provided at a second device output 24. The evaluation signal S is generated by an evaluation circuit 40 of the device 21. A third device output 23 is connected to ground M.

[0064] The evaluation signal S is, for example, a voltage or a current. It can have a first polarity S1 or a second polarity S2 opposite to the first polarity S1. For example, the first polarity is negative and the second polarity is positive. The polarities S1, S2 of the evaluation signal S can be constant during each phase and can be alternating during each phase (Figure 4). The evaluation signal S is shown as a square wave signal in Figure 4. Alternatively, the evaluation signal S can also have any other waveform during the phase with alternating polarities S1, S2, such as a sine wave or a triangular wave with a positive half-wave and a negative half-wave. During the alternating polarity S1, S2 phases, the evaluation signal S can be periodic or non-periodic. It is also possible that the duration of the half-wave with the first polarity and the duration of the half-wave with the second polarity have different lengths.

[0065] Preferably, the evaluation signal S has exclusively one polarity, for example a first polarity S1 in the initial condition. Thereby, the evaluation signal can have a constant magnitude.

[0066] The instrument 26 for coagulation and cutting is connected to the device 21 via a multi-core cable 25. The instrument 26 has a housing 27, which has a handle 28 and a tool 29. In this embodiment, the tool 29 is connected to the housing 27 via a connecting portion 30. The connecting portion 30 can be configured in a rod-shaped manner. An operating element 31 for the tool 29 is present on the handle 28. The operating element 31 is used for mechanical and electrical operation of the tool 29. A manually operable first switch 32 and a manually operable second switch 33 are provided on the operating element 31. In this embodiment, the two switches 32, 33 are configured as buttons and take a non-conductive condition in their initial condition when not operated.

[0067] exist Figure 2 middle, Figure 1 The tool 29 of the instrument 26 is shown in a partial perspective view. The tool 29 has two jaws 34, 35, which can be moved relative to each other and are connected to each other in an articulated manner by means of a hinge 41. The jaws 34, 35 can be pivoted relative to each other by means of an operating element 31. At least one first coagulation electrode 36 is arranged at one jaw 34, and at least one second coagulation electrode 37 is provided at the corresponding other jaw 35. A first coagulation electrode 36 and a designated second coagulation electrode 37 each form a coagulation electrode pair. A plurality of coagulation electrode pairs can be provided on the jaws 34, 35.

[0068] Furthermore, one jaw 34 additionally comprises a cutting electrode 38. In this embodiment, the cutting electrode 38 is arranged as an insert in a groove-like recess at the jaw 35 and is flanked by two first coagulation electrodes 36. The cutting electrode 38 is arranged on the tool 29 electrically isolated from the first coagulation electrodes 36. A plurality of first coagulation electrodes 36 can be electrically connected to one another.

[0069] A counter-support 39 for the cutting electrode 38 is arranged on the jaws 38. If the tool 29 is closed by the operating element 31, a first coagulation electrode 36 and a second coagulation electrode 37 are arranged opposite each other. The cutting electrode 38 is located next to the counter-support 39 or in contact with it. The electrical functions of the electrodes 36, 37, 38 can be operated by means of switches 32, 33.

[0070] An embodiment of the operating circuit 45 of the instrument 26 is Figure 3 4. The operating circuit 45 has a supply connector 46, by means of which the operating circuit 45 can be connected to the first device output 22, and a ground connector 47, by means of which the operating circuit 45 can be connected to the third device output 23. A signal connector 48 of the operating circuit 45 can be connected to the second device output 24. Thus, an evaluation signal S of the device 21 is provided at the signal connector 48. The operating circuit 45 is connected to the ground M via the ground connector 47. The supply connector 46 is connected to an RF current source or an RF voltage source 42 of the device 21 according to this example in order to provide the operating circuit 45 with a supply current IV or a supply voltage UV.

[0071] The supply connector 46 is connected to a coagulation output 50 via a first capacitor 49. The first coagulation output 50 is connected to the at least one first coagulation electrode 36. The second coagulation output 51 is connected to the at least one second coagulation electrode 37. In this embodiment, the second coagulation output 51 is configured as a ground output. To this end, the second coagulation output 51 is connected to the ground connector 47 and is therefore connected to the ground M.

[0072] In addition, the operating circuit 45 comprises a switching unit 53, which can be switched by means of a control signal A of the control element 52. The switching unit 53 is connected in the electrical connection between the supply connector 46 and the cutting output 54. The switching unit 53 is configured to provide a cutting voltage US and / or a cutting current at the cutting output 54 under a first switching condition (the first switching condition is configured to cut by using the cutting electrode 38), and to provide substantially no electrical energy at the cutting output 54 under a second switching condition. According to the example, under the second switching condition, the connection between the supply connector 46 and the cutting output 54 is interrupted.

[0073] The switch unit 53 is configured without a mechanical switch and includes at least one semiconductor switch 55 and in this embodiment includes two semiconductor switches 55 connected in series. According to this example, each semiconductor switch 55 is a field effect transistor, which is shown here as a normally non-conductive n-channel MOSFET. According to this embodiment, each semiconductor switch 55 has a control port 56 formed by the gate of the MOSFET.

[0074] The two control ports 56 are preferably connected to each other. In addition, the two source connections of the MOSFET can be connected to each other ( Fig.13 ).

[0075] In each case, the drain connections of two MOSFETs form a switch port 57 of the switch unit 53. The switching path of the switch unit 53 is formed between the two switch ports 57. One of the switch ports 57 of the switch unit 53 is connected to the supply connector 46. The respective other switch port 57 is connected to the cutting output 54.

[0076] According to the example, the switch unit 53 comprises a loading and unloading circuit 58 for the at least one semiconductor switch 55. The loading and unloading circuit 58 is configured to be able to maintain the charge at the control port 56 for a sufficiently long time so as to maintain the first switching condition of the switch unit 53 during the phases of alternating polarities S1, S2 of the evaluation signal S as long as the first switch 32 is operated. According to the example, the control signal A for maintaining the first switching condition is only generated in the case where the evaluation signal S has one of the two polarities S1 or S2, and according to the example has the second polarity S2. This results in that during the phases with alternating polarities S1, S2 of the evaluation signal S, the control signal A also changes its condition alternately. During such phases, the loading and unloading circuit 58 avoids the switching of the switch unit 53 alternately between the first and second switching conditions.

[0077] Furthermore, the loading and unloading circuit 58 is configured to dissipate the charge present at the control port 56 if the first switch 32 is no longer operating, so that the semiconductor switches 55 can again switch to their non-conducting condition (which, according to the example, corresponds to the second switching condition).

[0078] In this embodiment, the operating circuit 45 has a transformer circuit, which has a transformer 60. The transformer 60 includes a primary winding 61 and a secondary winding 62. In this embodiment, the transformer 60 is configured as an autotransformer. Thereby, the primary winding 61 and the secondary winding 62 are connected in series, and the tap 63 is connected to the designated switch port 57 of the switch unit 53. Starting from the tap 63, the series connection of the primary winding 61 and the second capacitor 64 is connected to the ground M. Starting from the tap 63, the series connection of the secondary winding 62 and the third capacitor 65 is connected to the cutting output 54. The first resistor 66 is connected in parallel with the third capacitor 65. The parallel connection of the third capacitor 65 and the first resistor 66 forms a spark detection circuit. If a spark occurs, the supply current IV includes a DC component, or the supply voltage UV includes a DC voltage component, which can be evaluated and detected in the device 21 as an option. If such a spark detection is not required, the spark detection circuit can also be omitted.

[0079] The operating circuit 45 further comprises a control circuit 70, of which the control element 52 is a part. The control circuit 70 is coupled to the switch unit 53 via a coupling device 71 in order to transmit the control signal A from the control circuit 70 to the switch unit 53. For this purpose, the coupling device 71 has at least one transmitter component 72 and at least one receiver component 73 in the control circuit 70, and the receiver component 73 is connected to at least one control port 56 of the switch unit 53. In this embodiment, the at least one transmitter component 72 is a light emitting diode, and the at least one receiver component 73 is a photodiode or alternatively a phototransistor. The coupling device 71 can be formed by an optical coupler 74. In the illustrated embodiment, the transmitter component 72 is implemented by the control element 52.

[0080] exist Figure 3 In the embodiment shown, the control circuit 70 comprises a first circuit branch 75 with a first switch 32, a second circuit branch 76 with a second switch 33 and a third circuit branch 77. The three circuit branches 75, 76, 77 are connected in parallel to each other between the ground connector 47 and the signal connector 48.

[0081] In this embodiment, the third circuit branch 77 is defined as a series connection of a first diode 78 and a second resistor 79. The cathode of the first diode 78 is connected to the signal connector 48 and the anode is connected to the second resistor 79. The other connection of the second resistor 79 is connected to ground M.

[0082] In addition to the second switch 33 , the second circuit branch 76 also comprises a third resistor 80 which is connected in series to the second switch 33 .

[0083] The first circuit branch 75 has a unidirectional current path 81 connected in series with the first switch 32 and a parallel current path 82 connected in parallel with the unidirectional current path. In the unidirectional current path 81, the control element 52 is connected in series with the first switch 32. The unidirectional current path 81 includes at least one component with a diode function, so that if the first switch 32 is closed, the current can only flow through the unidirectional current path 81 in one direction, and according to the example, from the signal connector 48 to the ground connector 47. In the embodiment shown here, an additional component with a diode function is connected in series to the control element 52, for example a second diode 83. The anode of the second diode 83 is connected to the signal connector 48, and the cathode of the second diode 83 is connected to the control element 52, and according to the example, the anode of the light emitting diode forms the control element 52.

[0084] Furthermore, in the illustrated embodiment, the connection point between the second diode 83 and the control element 52 is connected to the second switch 33 via a connecting current path 84 , so that the connecting current path 84 and the second switch 33 are connected in parallel to the control element 52 and the first switch 32 .

[0085] In the parallel current path 82 , the fourth resistor 85 is connected in parallel to the second diode 83 and the control element 52 .

[0086] The function of the operating circuit 45 is then explained based on FIGS. 4-12. For the purpose of distinction, the current flowing through the first circuit branch 75 is referred to as the first current I1, the current flowing through the second circuit branch 76 is referred to as the second current I2, and the current flowing through the third circuit branch 77 is referred to as the third current I3 ( Figure 7-12 ). The resistance values ​​of the resistors 79, 85 and 80 in the circuit branches 75, 76, 77 are selected so that the evaluation circuit 40 of the device 21 detects whether the first switch 32, the second switch 33 or both switches 32, 33 are in a conductive condition based on the amount of the currents I1, I2, I3. In particular, the resistance values ​​of the third resistor 80 and the fourth resistor 85 have different amounts.

[0087] The control circuit 70 is configured to influence the characteristics of the evaluation signal S provided by the evaluation circuit 40. In this embodiment, for this purpose, the control circuit 70 changes the amount of the evaluation current flowing between the second device output 24 and the third device output 23 as a function of the switching conditions of the two switches 32, 33. The evaluation circuit 40 can measure the amount of the evaluation current flowing between the second device output 24 and the third device output 23 (ground M), for example by means of a measuring resistor.

[0088] This possibility of varying the amount of the evaluation current through the control circuit 70 allows a simple detection of the switching conditions of the first switch 32 and the second switch 33. As an alternative to this, other characteristics of the evaluation signal S can also be modified depending on which of the circuit branches 75, 76 the current flows through, for example by varying the voltage level by means of Zener diodes of different sizes in the circuit branches 75, 76 or by active components in the circuit branches which modulate the voltage or current in a different manner, etc.

[0089] In all cases, the evaluation circuit 40 of the device 21 is able to detect, based on the characteristics of the evaluation signal S conditioned by the control circuit 70, whether the first switch 32 and / or the second switch 33 is operated and thus switched to the conductive condition, so that it can be detected whether the operator requests the cutting mode or the coagulation mode. By operating the first switch 32, the cutting mode is requested, and by operating the second switch 33, the coagulation mode is requested.

[0090] In this embodiment, the evaluation signal S is constant under initial conditions and comprises exclusively a first polarity S1 which is negative according to the example, as schematically shown in FIG. 4 .

[0091] In the initial condition of the evaluation signal S, it is assumed that both switches 32, 33 are not operated and are therefore non-conductive ( Figure 7 ). Due to the negative potential at the signal connector 48, only a current can occur from the ground connector 47 to the signal connector 48. Since the switches 32 and 33 are not conducting, the first circuit branch 75 and the second circuit branch 76 are interrupted. Therefore, only the third current I3 can flow through the third circuit branch 77. The amount of the third current I3 is evaluated in the evaluation circuit 40, and it is recognized from this that the two switches 32, 33 are not operating and are therefore not conducting.

[0092] Assume that the operator actuates the first switch 32 at a first time t1 to request the cutting mode, so that it is switched to its on condition ( Figure 8 ). In addition to the third current I3 flowing through the third circuit branch 77, the first current I1 can now flow via the first switch 32 and through the fourth resistor 85 in the parallel current path 82. Thus, the total resistance of the control circuit 70 is obtained substantially from the parallel connection of the second resistor 79 and the fourth resistor 85. The amount of the evaluation current corresponds to the sum of the amounts of the first current I1 and the second current I3, and the second current I3 changes compared to the non-actuated condition ( Figure 7 ). This change can be detected in the evaluation circuit 40 .

[0093] Thus, it is recognized in the device 21 that the operator has actuated the first switch 32. The evaluation circuit 40 is configured to start the cutting mode in this case and to control the instrument 26 accordingly. First, at a first time t1, a supply voltage UV is provided at the first device output 22 via an activation signal W, so that a coagulation voltage UK is applied between a first coagulation output 50 and a second coagulation output 51 provided by the RF voltage source 42 (FIG. 5).

[0094] Starting from the first time t1 at which the first switch 32 has been actuated, the first phase P1 starts in cutting mode. During this first phase P1, the evaluation signal S maintains the first polarity S1, whereby the switch unit 53 assumes its second switching condition. Thus, there is no cutting voltage US or no cutting current at the cutting output 52. According to this example, under the second switching condition of the switch unit 53, the voltage and current at the cutting output 54 are substantially equal to zero. In a modified embodiment, the switch unit 53 can establish a connection between the supply connector 46 and the cutting output 54 under the second switching condition, and under the second switching condition, the transformer 60 is bypassed so that the coagulation voltage UK is also applied to the cutting output 54.

[0095] If a condition for terminating the first phase P1 is met (eg expiration of a predetermined duration), the first phase P1 is terminated. Additionally or alternatively, the coagulation current through the device 21 achieved by the coagulation voltage UK may be evaluated and the first phase P1 may be terminated if the coagulation current drops below a threshold.

[0096] After the first phase P1 terminates (second time t2), the second phase P2 starts directly. In this second phase P2, the cutting voltage US is applied to the cutting output 54. To this end, the switching unit 53 must switch from the second switching condition to the first switching condition. According to this example, this is achieved by the evaluation circuit 40 changing the evaluation signal S during the second phase P2 so that it includes alternating polarities S1, S2. During this second phase P2, the evaluation signal S can be an AC voltage with a positive half-wave and a negative half-wave. The amplitudes of the positive half-wave and the negative half-wave can have equal or different amounts. The duration of the positive half-wave and the negative half-wave can have equal or different lengths.

[0097] During the positive half wave, if the evaluation signal S has the second polarity S2, the current flow direction is reversed in the control circuit 70 and the evaluation current flows from the signal connector 48 to the ground connector 47 ( Fig. 9 Due to the inoperable second switch 33, the second circuit branch 76 is interrupted and due to the first diode 78, no current can flow through the third circuit branch 77 in the direction towards the ground connector 47. Only the first current I1 flows through the first circuit branch 75.

[0098] Thus, the first current I1 includes a partial current I11 passing through the unidirectional current path 81 and a second partial current I12 passing through the parallel current path 82. Due to the small resistance value compared to the resistance value of the fourth resistor 85, the partial current I11 passing through the unidirectional current path 81 is significantly higher than the second partial current I12 passing through the parallel current path 82. The partial current I11 flows through the control element 52, which is also the transmitter component 72 in this embodiment. In doing so, a control signal A is generated and transmitted to the receiver component 73. The receiver component 73 then initiates the switching of the switch unit 53 from the second switching condition to the first switching condition. Under the first switching condition, the at least one semiconductor switch 55 is turned on, so that an electrical connection is established between the switch ports 57 of the switch unit 53. The electrical connection is established between the supply connector 46 and the tap 63 of the transformer 60. This electrical connection is established by setting a cut output 54 ( Figure 6 ) provides a conversion of the supply voltage UV applied at the supply connector 46 into a cutting voltage US.

[0099] According to this example, the control signal A is formed by light transmitted from the light emitting diode (emitter component 72) of the optocoupler. The light emitting diode of the optocoupler 74 only emits light if current flows through the light emitting diode. The emitted light (control signal A) in turn provides a voltage generated by the at least one photodiode of the optocoupler 74, which acts as a source for generating a drain-source voltage or a base-emitter voltage through the load and unload circuit 58, so that the at least one semiconductor switch 55 can be switched to a conductive condition or can be maintained in a conductive condition.

[0100] If a condition for terminating the second phase P2 is met, the second phase P2 is terminated. For example, this may be the termination of a predetermined duration of the second phase P2. A condition for terminating the second phase P2 may also be met if the cutting current flowing through the tissue from the cutting output 54 drops below a threshold value, which may be assessed by the device 21.

[0101] like Figure 6 As shown, the second phase P2 ends at the third time t3. At time t3, the third phase P3 begins. During the third phase P3, the evaluation circuit 40 generates an evaluation signal S corresponding to the initial condition and therefore only includes the first polarity S1 (with a constant amount according to the example). If the condition for terminating the third phase P3 is met (for example, if the predetermined duration expires), the third phase P3 is terminated.

[0102] During the third phase P3 the coagulation voltage UK is maintained between the two coagulation outputs 50, 51. After the end of the third phase P3 (fourth time t4), the evaluation circuit 40 cuts the supply voltage UV by means of the activation signal W. The cutting is completed.

[0103] The third stage P3 is optional and can also be omitted.

[0104] Since the evaluation signal S also comprises the first polarity S1 at least during a time period during each phase P1, P2, P3, this at least one time period can be used to determine whether the first switch 32 is still operated. If the operator releases the first switch 32 before the cutting is terminated, this is determined and the supply voltage UV for the instrument 26 is switched off by means of the activation signal W. The cutting process can thus be interrupted in each phase P1, P2, P3 of the dissection.

[0105] For example, in Fig.10 3 shows the situation in which, as long as the evaluation signal S is applied in its initial condition (exclusively, the first polarity S1), the operator operates the second switch 33. In doing so, an evaluation current ( ) is generated which includes a second current I2 through the second circuit branch 76 and a third current I3 through the third circuit branch 77. Fig.10 ). As already explained, the evaluation circuit 40 can detect the amount of the evaluation current formed by the sum of the second current I2 and the third current I3, and can detect that the second switch 33 has been operated. In this case, the total resistance of the control circuit 70 is substantially obtained by the parallel connection of the second resistor 79 and the third resistor 80.

[0106] The closing of the second switch 33 signals that the operator requests the coagulation mode. By reference to FIGS. 4-6 , it is assumed, as an example, that the second switch 33 has been operated at a first time t1. Similar to the cutting mode, the application of the supply voltage UV at the first device output 22 is initiated by the activation signal W with the aid of the evaluation circuit 40, so that the coagulation voltage UK is applied to the first coagulation output 50 ( FIG. 5 ). In the case of the clear-cut coagulation mode, the evaluation signal S is not modified and maintains its initial condition. Therefore, the switch unit 53 remains in its second switching condition and no cutting voltage US is applied to the cutting output 54 ( Figure 6 dotted line in the figure).

[0107] Similar to the cutting mode, also in the coagulation mode the generation of the coagulation voltage UK can be associated with a termination condition and can be terminated by evaluating the coagulation current according to the example or after expiration of the duration, as already explained in connection with the cutting mode.

[0108] Fig.11, a situation is shown in which the operator operates the first switch 32 as well as the second switch 33 if the evaluation signal S comprises an initial condition which exclusively has the first polarity S1. In this case, the amount of the evaluation current comprises the sum of the amounts of the first current I1 through the first circuit branch 75, the second current I2 through the second circuit branch 76 and the third current I3 through the third circuit branch 77. The total resistance of the control circuit 70 is substantially obtained by the parallel connection of the second resistor 79, the third resistor 80 and the fourth resistor 85. The evaluation circuit 40 of the device 21 can therefore determine that both switches 32, 33 have been actuated because the amount of the evaluation current is evaluated.

[0109] One possibility in this case is that the evaluation signal S maintains the condition of exclusively having the first polarity S1 and activates only the coagulation mode as described above. If the evaluation signal S does not include a portion having the second polarity S2, the control signal A capable of switching the switching unit 53 under the first switching condition is not generated. The generation of the cutting voltage US for cutting is omitted.

[0110] Even if the evaluation signal S also includes periods with alternating polarities S1, S2 similarly to the cutting mode, the switching of the switching unit 53 is also hindered in the first switching condition (compare Fig.12 ). Since the second switch 33 bypasses the control element 52, a current flow through the control element 52 is avoided and in doing so, no control signal is generated that could initiate switching of the switch unit 53 under the first switching condition. In this case, the generation of the cutting voltage US is also avoided.

[0111] The at least one receiver component 73 is connected to the control port 56 of each semiconductor switch 55 via a loading and unloading circuit 58 so that on the one hand the charge in the control port 56 can be maintained for a sufficiently long time (at least during the duration of the first half-wave with the first polarity S1) and on the other hand the charge present there can be dissipated again if the switching unit 53 is to be switched under the second switching condition.

[0112] In this embodiment, the charge in the gate connection of the MOSFET is maintained via the loading and unloading circuit 58, so that if there is a half-wave with the first polarity S1 during the second phase P2, the switching unit 53 is also kept in its second switching condition (conducting condition). At least for the duration of the half-wave with the first polarity S1, if the photodiode of the optocoupler 74 is again controlled by the light-emitting diode of the optocoupler 74, if the first switch 32 is turned on during the second half-wave S2, the charge in the gate of the MOSFET is maintained by the loading and unloading circuit 58.

[0113] Fig.13An embodiment of a load and unload circuit 58 is shown. Obviously, other load and unload circuits may be used.

[0114] The at least one receiver component 73 has a first port 73a of higher potential (here: anode side of the at least one photodiode) and a second port 73b of lower potential (here: cathode side of the at least one photodiode). During activation by the transmitter component 72, a higher potential is applied at the first port 73a than at the second port 73b.

[0115] A fifth resistor 90 is connected in parallel to the at least one receiver component 73. An anode of a third diode 91 is connected to the first port 73a, and a cathode of the third diode 91 is connected to a fourth capacitor 92. The other side of the fourth capacitor 92 is connected to the second port 73b. The fifth resistor 90 is connected in parallel to the series connection of the third diode 91 and the fourth capacitor 92.

[0116] The series connection of the fourth diode 93 and the fifth capacitor 94 is connected in parallel with the third diode 91, wherein the anode of the fourth diode 93 is connected to the cathode of the third diode 91. The cathode of the fourth diode 93 is connected to the anode of the fifth diode 95. The cathode of the fifth diode 95 is connected to the sixth capacitor 96. The other connection of the sixth capacitor 96 is connected to the second port 73b. In addition, the sixth capacitor 96 is connected between the control port 56 (drain connection) and the connection point between the two semiconductor switches 55 (source connection) connected in series. A sixth resistor 97 is connected in parallel with the sixth capacitor 96.

[0117] A plurality of cascades of one diode 91, 93, 95 and capacitors 92, 94, 96 connected in series, respectively, serve for voltage multiplication of the voltage applied to the at least one receiver component 73 during activation by the transmitter component 72. Due to the provided capacitors, the activation of the semiconductor switch 55 and according to this example, during the half-wave with the first polarity S1, the charge in the gate of the field effect transistor can also be maintained if no voltage is applied to the at least one receiver component 73 for a short period of time. Thus, the capacitor acts as a buffer capacitor. To allow unloading, resistors 90, 97 of the loading and unloading circuit 58 are provided. If the first switch 32 is not activated, the charge in the control port 56 can be leveled off via the resistors 90, 97 and the semiconductor switches 55 can return to their blocking condition. The duration from the switching of the first switch 32 in the non-conducting condition until the semiconductor switch 55 is blocked depends on the size of the components present in the loading and unloading circuit 58.

[0118] In modifications to the above described loading and unloading circuit 58 , it is also possible to use more or fewer cascades of diodes and capacitors, depending on which voltage is required to activate the semiconductor switch 55 .

[0119] Fig.14 A modified embodiment of the switch unit 53 is shown. The semiconductor switch 55 comprises a bipolar transistor 103 and is controlled by a semiconductor control switch 102, respectively. According to this example, the semiconductor control switch 102 is a field effect transistor, typically a non-conducting n-channel MOSFET. The control port 56 of the semiconductor control switch 102 is connected to the loading and unloading circuit 58. In addition, the two collectors of the bipolar transistor 103 are connected to the loading and unloading circuit 58. Each emitter of one bipolar transistor 103 forms a switch port 57. The collector of the bipolar transistor 103 is additionally connected to the source connection of the field effect transistor forming the semiconductor control switch 102. The base of each bipolar transistor 103 is connected to the drain connection of the corresponding designated field effect transistor. Once the gate-source voltage is high enough, the semiconductor control switch 102 becomes conductive, so that the base current flows out of the PNP-bipolar transistor 103, and they transition to their conductive condition.

[0120] Fig.15 A modified embodiment of the third circuit branch 77 is shown in . Instead of the first diode 78, a transistor, in particular a bipolar transistor, can be used, whose collector connection is connected to the second resistor 79 and whose emitter connection is connected to the signal connector 48. The base connection of the transistor is connected to ground via a seventh resistor 101.

[0121] The present invention relates to a device 20 and a method for coagulating and / or dissecting biological tissue. The device 20 comprises a device 21 and an instrument 26 electrically connected to the device 21. On the instrument 26, at least a first switch 32 is provided for manual operation, which is part of an operating circuit 45. An evaluation circuit 40 of the device 21 provides an evaluation signal S for the instrument 26. In addition, the device 21 can generate a supply voltage UV or alternatively supply a current IV and provide it to the instrument 26. Under initial conditions, the evaluation signal S only includes one polarity and is always higher than or equal to zero under the initial conditions, or is always less than or equal to zero, but not continuously, but at most temporarily equal to zero. The evaluation signal S is provided to a control circuit 70 of the instrument 26, wherein the characteristics of the evaluation signal S are adjusted according to the operating conditions of the first switch 32. The evaluation circuit 40 of the device 21 detects this characteristic and can determine whether the operator activates the cutting mode via the first switch 32 based on it. The evaluation circuit 40 can then cause the device 21 to provide the instrument 26 with a supply voltage UV or a supply current IV and the evaluation signal S changes depending on the requested cutting mode, in particular with regard to its polarity S1, S2. In the cutting mode, the evaluation signal S at least temporarily also comprises a second polarity S2.

[0122] List of reference numerals:

[0123] 20 Device for coagulation and cutting

[0124] 21 Equipment

[0125] 22 First device output

[0126] 23 Third device output

[0127] 24 Second device output

[0128] 25 Cable

[0129] 26 Instruments

[0130] 27 Housing

[0131] 28 Handle

[0132] 29 Tools

[0133] 30 Connection part

[0134] 31 Operating elements

[0135] 32 First switch

[0136] 33 Second switch

[0137] 34 Clamp

[0138] 35 Clamp

[0139] 36 First coagulation electrode

[0140] 37 Second coagulation electrode

[0141] 38 Cutting Electrode

[0142] 39 Counter support

[0143] 40 Evaluation Circuit

[0144] 41 Hinge

[0145] 42 Voltage Source

[0146] 45 Operation Circuit

[0147] 46 Supply Connector

[0148] 47 Ground Connector

[0149] 48 Signal connector

[0150] 49 First capacitor

[0151] 50 First coagulation output

[0152] 51 Second coagulation output

[0153] 52 Control elements

[0154] 53 Switching unit

[0155] 54 Cutting output

[0156] 55 Semiconductor switch

[0157] 56 Control Port

[0158] 57 switch ports

[0159] 58 Loading and unloading circuits

[0160] 60 Transformer

[0161] 61 Primary winding

[0162] 62 Secondary Winding

[0163] 63 tap

[0164] 64 Second capacitor

[0165] 65 The third capacitor

[0166] 66 First resistor

[0167] 70 Control circuit

[0168] 71 Coupling device

[0169] 72 Transmitter Parts

[0170] 73 Receiver Parts

[0171] 73a First Port

[0172] 73b Second port

[0173] 74 Optocoupler

[0174] 75 First circuit branch

[0175] 76 Second circuit branch

[0176] 77 Third Circuit Branch

[0177] 78 First diode

[0178] 79 Second resistor

[0179] 80 Third resistor

[0180] 81 Unidirectional current path

[0181] 82 Parallel current paths

[0182] 83 Second diode

[0183] 84 Connecting current path

[0184] 85 Fourth resistor

[0185] 90 Fifth resistor

[0186] 91 The third diode

[0187] 92 Fourth capacitor

[0188] 93 Fourth diode

[0189] 94 Fifth capacitor

[0190] 95 Fifth diode

[0191] 96 Sixth capacitor

[0192] 97 Sixth resistor

[0193] 100 transistors

[0194] 101 Seventh Resistor

[0195] 102 semiconductor control switch

[0196] 103 Bipolar Transistor

[0197] A Control signal

[0198] I Current

[0199] I1 First current

[0200] I11 partial current

[0201] I12 partial current

[0202] I2 Second current

[0203] I21 Partial Current

[0204] I22 partial current

[0205] I3 Third current

[0206] IV Supply Current

[0207] M Land

[0208] P1 Phase 1

[0209] P2 Phase 2

[0210] P3 Phase 3

[0211] S Evaluation signal

[0212] S1 First polarity

[0213] S2 Second polarity

[0214] t1 first time

[0215] t2 Second time

[0216] t3 Third time

[0217] t4 fourth time

[0218] UK coagulation voltage

[0219] US cutting voltage

[0220] UV supply voltage

Claims

1. A device (20) for coagulating and / or cutting biological tissue, comprising a device (21) and an instrument (26) electrically connected to the device (21), in, The device (21) is configured to provide a supply voltage (UV) or a supply current (IV) at a first device output (22), and wherein the device (21) comprises an evaluation circuit (40) configured to provide an evaluation signal (S) at a second device output (24), Wherein, the operating circuit (45) of the instrument (26) comprises: a supply connector (46) connectable to said first device output (22), a signal connector (48) connectable to said second device output (24), a control circuit (70) connected to the signal connector (48), configured to generate a control signal (A) depending on the polarity (S1, S2) of the evaluation signal (S) and comprising a first manually operable switch (32), a switching unit (53) which is controllable by the control signal (A) and is switchable between a first switching condition and a second switching condition and is connected to the supply connector (46) and the cutting output (54), - wherein the control circuit (70) is configured to adjust the characteristics of the evaluation signal (S) depending on the operating conditions of the first switch (32), and wherein the evaluation circuit (40) is configured to detect the characteristics of the evaluation signal (S) and adjust the polarity (S1, S2) of the evaluation signal (S) according to the characteristics.

2. The device according to claim 1, wherein: If the characteristics of the evaluation signal (S) indicate that the first switch (32) has been operated, the evaluation signal (S) includes only a first polarity (S1) during a first phase (P1) starting with the operation of the first switch (32), and includes the first polarity (S1) and a second polarity (S2) opposite to the first polarity in an alternating manner during a second phase (P2).

3. The device according to claim 2, wherein: The control circuit (70) is configured to cause the switching unit (53) to assume the first switching condition by means of the control signal (A) if the evaluation signal (S) at least temporarily includes the second polarity (S2) during the second phase (P2), wherein, under the first switching condition suitable for cutting biological tissue, an electric cutting voltage (US) or an electric cutting current is provided at the cutting output (54).

4. The device according to claim 2 or 3, wherein: The control circuit (70) is configured to: if the evaluation signal (S) during the first phase (P1) only includes the first polarity (S1), then with the help of the control signal (A) the switching unit (53) assumes the second switching condition, wherein under the second switching condition, no electric cutting voltage (US) and no electric cutting current are provided at the cutting output (54).

5. The device according to any one of claims 1 to 3, wherein: The device (21) comprises a controllable voltage source (42) or current source, and wherein the evaluation circuit (40) is configured to control the voltage source (42) or current source by means of an activation signal (W).

6. The device according to claim 2 or 3, characterized in that: The control circuit (70) comprises a second switch (33) which is manually operable.

7. The device according to claim 6, wherein: The control circuit (70) is configured to adjust a characteristic of the evaluation signal (S) according to an operating condition of the second switch (33), and wherein the evaluation circuit (40) is configured to detect a characteristic of the evaluation signal (S) and to adjust a polarity (S1, S2) of the evaluation signal (S) according to the characteristic.

8. The device according to claim 7, wherein: The device (21) comprises a controllable voltage source (42) or a current source, and the evaluation circuit (40) is configured to generate an activation signal (W) to control the voltage source (42) or the current source so that: if the characteristics of the evaluation signal (S) indicate that the first switch (32) and / or the second switch (33) have been actuated, the controllable voltage source (42) or the current source provides the supply voltage (UV) or the supply current (IV) at the first device output (22).

9. The device according to claim 7 or 8, wherein: The evaluation circuit (40) is configured to generate an evaluation signal (S) comprising only the first polarity (S1) if a characteristic of the evaluation signal (S) indicates that the second switch (33) has been actuated.

10. The device according to any one of claims 1 to 3, wherein: The control circuit (70) is configured to adjust the amount of the evaluation signal (S) as a characteristic of the evaluation signal (S) according to an operating condition of the first switch (32).

11. The device according to any one of claims 1 to 3, wherein: The instrument (26) comprises a tool (29) having at least one cutting electrode (38), at least one first coagulation electrode (36) and at least one second coagulation electrode (37).

12. The device according to claim 11, wherein The cutting output (54) is connected to the at least one cutting electrode (38), and wherein the first coagulation output (50) of the operating circuit (45) is connected to the at least one first coagulation electrode (36), and the second coagulation output (51) of the operating circuit (45) is connected to the at least one second coagulation electrode (37).

13. The device according to any one of claims 1 to 3, characterized in that The first switch (32) and a control element (52) configured to generate the control signal (A) are connected in series in a first circuit branch (75), wherein the first circuit branch (75) is connected to the signal connector (48).

14. The device according to claim 13, wherein: The control circuit (70) comprises a manually operable second switch (33) arranged in a second circuit branch (76), wherein the second circuit branch (76) is connected to the signal connector (48).

15. The device according to any one of claims 1 to 3, characterized in that The operating circuit (45) comprises a transformer circuit (60) which is connected on its primary side to the supply connector (46) and on its secondary side to the cutting output (54).

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