GENERATOR FOR DELIVERING HIGH-FREQUENCY ACTING CURRENT TO A MEDICAL INSTRUMENT

Description

[0001] The invention relates to a generator for supplying high-frequency alternating current to a medical instrument, for example, for cutting and / or coagulating biological tissue. The generator has terminals to which a suitable instrument can be connected in order to electrically connect the instrument to the generator and supply it with high-frequency alternating current during operation. The generator and instrument together form a high-frequency or RF surgical device.

[0002] High-frequency (HF) surgical devices have long been established technology. The HF energy generated and delivered by the device is used, for example, for cutting or coagulation on the human body. For this application, an electrosurgical instrument, through which the HF energy is introduced into the tissue, is connected to the generator. In a monopolar application, a separate neutral or return electrode is also connected, which serves to return the energy to the HF surgical device. In a bipolar application, the return electrode is integrated into the instrument.

[0003] Modern generators for electrosurgical devices that meet current safety requirements feature an application unit and a galvanically isolated intermediate circuit. The electrosurgical instrument is connected to the generator's application unit. Thus, during electrosurgical procedures, the application unit is in direct contact with the patient's tissue. The application unit and the intermediate circuit are galvanically isolated from each other for the safety of both the patient and the user. An example of such an electrosurgical device is described in DE 10 2010 025298 A1. Other electrosurgical devices are described in US 2003 / 0036757 A1, DE 33 29 582 A1, US 2005 / 0101947 A1, and DE 34 27 517 A1.

[0004] The object of the present invention is to provide an improved RF surgical device that offers high operational reliability.

[0005] According to the invention, this problem is solved by a generator for supplying high-frequency alternating current to a medical instrument, comprising a power supply unit, a high-frequency generator primary unit (HF generator primary unit), an application unit, and a control unit. The HF generator primary unit is connected to the power supply unit and the application unit and is configured to supply the application unit with high-frequency alternating current during operation. The application unit is electrically connected via at least one relay with terminals for connecting a medical instrument. The control unit is galvanically isolated from the application unit and is configured to control the at least one relay and, optionally, the application unit. The control unit is connected to the application unit via an intermediate control circuit, which is galvanically isolated from both the control unit and the application unit.The intermediate control circuit is designed to receive control signals from the control unit during operation of the generator and, depending on these control signals, to generate relay control signals and output them to at least one relay of the application unit.

[0006] An intermediate control circuit according to the invention offers the advantage that the relay coils and the feedback contacts of the relays controlled by the intermediate control circuit can be designed with significantly smaller insulation distances. This allows, for example, smaller relays to be used. This leads to savings in space and weight. The reason for the potentially smaller insulation distances is that the intermediate control circuit can be designed such that the maximum potential difference between the application unit and the intermediate control circuit—and thus the isolation voltage for which the relays must be designed—can be lower if the intermediate control circuit is galvanically isolated from the generator's control unit, so that a larger maximum potential difference is already permissible between the generator's intermediate circuit and the intermediate control circuit.At this interface, such a higher maximum potential difference results in less effort required to achieve a correspondingly high insulation voltage.

[0007] The RF primary unit and control unit can be implemented on a single circuit board, forming a primary power supply and control unit. The intermediate control circuit then forms a galvanically isolated secondary control unit, which controls and reads the outputs of the relays switching the application unit.

[0008] Preferably, the voltage supply to the intermediate control circuit is provided by transformers arranged between the intermediate control circuit and the control unit, for example DC transformers such as DC / DC converters.

[0009] For signal transmission from the control unit to the intermediate control circuit, transmitters such as optocouplers are preferably used.

[0010] The intermediate control circuit preferably includes a relay control unit, for example a controller, which is connected on one side to the at least one relay in order to control it and read its feedback contacts. On the other side, the relay control unit is connected to the control unit via transformers, for example optocouplers, and can thus exchange control signals with the control unit.

[0011] Since the relay control unit can be designed as a controller, fewer signal transmitters, for example fewer optocouplers, can be provided between the intermediate control circuit and the control unit than relays need to be controlled, because more complex, coded signals can also be transmitted via the signal transmitters, which can be decoded by the relay control unit and converted into relay control signals for several relays.

[0012] This also contributes to the fact that only a few high-voltage-resistant components, such as optocouplers or DC-DC converters, need to be used between the control unit and the intermediate control circuit. This makes it easier to implement an isolation voltage of more than 2 kV between the control unit and the intermediate control circuit, for example, more than 4 kV. Conversely, this allows the isolation voltage between the intermediate control circuit and the application unit to be limited to a maximum of 1 kV, so that the relays only need to be designed for this isolation voltage.

[0013] The application unit of the generator preferably comprises a high-frequency generator circuit which, together with the RF generator primary unit, forms a high-voltage transformer, so that the application unit is also galvanically isolated from the RF generator primary unit. This again allows the RF generator primary unit and the control unit to operate at a common potential level, so that the control unit and the RF generator primary unit do not need to be galvanically isolated from each other.

[0014] The invention will now be explained in more detail using an exemplary embodiment with reference to the figures. The figures show... Figure 1 shows a schematic block diagram of a generator according to the invention, and Figure 2 shows a second, schematic representation of the generator according to the invention.

[0015] The in Figure 1The illustrated generator 10 has a power supply unit 12, which is connected to an RF generator primary unit 14 and a control unit 16 of the generator 10 and supplies these components of the generator with energy. For example, the RF generator primary unit 14 and the control unit 16 can be connected to the power supply unit 12 via a transformer 18. The power supply unit 12 can also be a battery power supply or some other type of power supply unit.

[0016] Part of the RF generator primary unit 16 is a primary coil of a high-frequency transformer 20, the secondary side of which is part of an application unit 22. The application unit 22 has a high-frequency generator circuit 24, which is configured to generate a high-frequency high voltage that can be supplied, for example, to a medical instrument connected to the generator 10 during its operation. For this purpose, the high-frequency generator circuit 24 is connected via relays 26 to terminals 28 for connecting one or more medical instruments. The connection between the high-frequency generator circuit 24 and the terminals 28 can be switched via the relays 26.

[0017] The control of the relays 26 and the reading of their read contacts are carried out by an intermediate control circuit 30, which includes a relay control unit 32. The intermediate control circuit 30 is connected to the control unit 16 via a DC / DC converter 34 and optocouplers 36. This provides galvanic isolation between the intermediate control circuit 30 and the control unit 16. The DC / DC converter 34 supplies power to the intermediate control circuit 30. The optocouplers 36 transmit control signals between the control unit 14 and the relay control unit 32 of the intermediate control circuit 30.

[0018] The relay control unit 32 is configured to convert control signals received from the control unit 16 via the optocouplers 36 into relay control signals, which can be used to individually control the relays 26. Furthermore, the relay control unit 32 can read the feedback contacts of the relays 26 and generate corresponding control signals, which the relay control unit 32 can transmit to the control unit 16 via the optocouplers 36. The optocouplers 36, the DC / DC converter 34, and the corresponding distances between the intermediate control circuit 30 and the control unit 16 are selected such that the isolation voltage between the control unit 16 and the intermediate control circuit 30 is, for example, 4 kV.On the other hand, the isolation voltage between the intermediate control circuit 30 and the application circuit 22 only needs to be, for example, 1 kV, so that it is sufficient to dimension the relays 26 for an isolation voltage of 1 kV and not for the maximum output voltage of the generator 10 of, for example, 5 kV. Reference symbol list

[0019] 10 Generator 12 Power supply unit 14 High-frequency generator primary unit (HF generator primary unit) 16 Control unit 18 Transformer 20 High-frequency transformer 22 Application unit 24 High-frequency generator circuit 26 Relay 28 Connections 30 Intermediate control circuit 32 Relay control unit 34 DC / DC converter 36 Optocoupler

Claims

1. A generator (10) for the delivery of high frequency alternating current to a medical instrument, the generator having a power supply unit (12), an HF generator primary unit (14), an application unit (22) and a control unit (16), wherein the HF generator primary unit (14) is connected to the power supply unit (12) and the application unit (22) and designed to supply the application unit (22) with high frequency alternating current during operation, wherein the application unit (22) via at least one relay (26) is electrically connected in a switchable manner to terminals (28) for connecting a medical instrument, and wherein the control unit (16) is galvanically separated from the application unit (22) and designed to control the at least one relay (26) and the application unit (22) as applicable, characterized in that the control unit (16) is connected to the application unit (22) via an intermediate control circuit (30), wherein the intermediate control circuit (30) is galvanically separated both from the control unit (16) and from the application unit (22) and the intermediate control circuit (30) is designed to receive during the operation of the generator (10) control signals from the control unit (16) and to generate relay control signals in dependence on said control signals and to output the relay control signals to the at least one relay (26) of the application unit (22).

2. A generator (10) pursuant to claim 1, characterized in that the intermediate control circuit (30) is connected to the control unit (16) via at least one optocoupler (36), wherein the optocoupler (36) is designed to transmit control signals from the control unit (16) to the intermediate control circuit (30), and wherein the intermediate control circuit (30) has a relay control unit (32) that is designed to process the control signals received from the control unit (16) and to generate relay control signals in dependence on the received control signals.

3. A generator (10) pursuant to claim 2, characterized in that the application unit (22) has several relays (26) and that the number of optocouplers (36) between the control unit (16) and the intermediate control circuit (30) is smaller than the number of relays (26).

4. A generator (10) pursuant to at least one of the previous claims, characterized in that an isolation voltage between the control unit (16) and the intermediate control circuit (30) is higher than 2 kilovolt, while the isolation voltage between the intermediate control circuit (30) and the application unit (22) is no higher than 1 kV.

5. A generator (10) pursuant to at least one of the previous claims, characterized in that the application unit (22) has a high frequency generator circuit (24) that is connected to the HF generator primary unit (14) and designed to supply a connected medical instrument with high frequency high voltage during operation, wherein the high frequency generator circuit (24) is electrically connected in a switchable manner to the terminals (28) for connecting a medical instrument via the at least one relay (26).