Surgery – Instruments – Electrical application
Reexamination Certificate
1998-03-12
2001-07-17
Peffley, Michael (Department: 3739)
Surgery
Instruments
Electrical application
Reexamination Certificate
active
06261285
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a high-frequency (HF) surgical device and an operation monitoring device for high-voltage relays which find use in generic type HF-surgical devices and a process for monitoring the operation of high-voltage relays for surgical devices.
STATE OF THE ART
HF-surgical devices of this type are common knowledge. German A-documents 31 51 991, 39 11 416 or 39 42 998 are referred to only by way of example. Moreover, reference is explicitly made to these printed publications for the explanation of all details not described in detail herein or other technical design of HF-surgical devices.
The known HF-surgical device, like other electro-medical devices, have the following problems:
According to IEC
601
, electro-medical devices require galvanic separation between the mains-side power supply and the patient/user unit. This galvanic separation occurs in the known generic-type HF-surgical devices by means of a separation transformer which may be either a mains transformer which is connected on the primary side immediately to the mains alternating voltage or is a component of a primary timed combinational mains circuit unit.
High performance high-frequency surgical devices have an output power of 400 W, if need be even more. This means that, depending on the degree of effectivity, approximately 600 W or more power has to be made available at the input side.
A mains transformer designed as a separation transformer, therefore, becomes very voluminous and correspondingly heavy. If a combinational mains circuit unit is employed, the required transformer is small, because usually frequencies between 50 and 100 kHz are worked with, but the cost of the transformer compared to the overall costs cannot be ignored. Moreover, the volume of the device increases.
Another problem with high-frequency surgical devices having more than one outlet respectively several generators is caused by one certain outlet has to be connected to a different generator depending on the mode of operation, by way of illustration cutting or coagulating, bipolar, monopolar etc., is to be employed. In order not to endanger the patient or user, it must be ensured that the high-frequency energy is switched only to the selected outlet.
For switching between the outlets and the generators, a relay matrix having make contacts as operating contacts is employed in order that the outlets are no longer connected to the generator electronics when the device is switched off respectively the switched-off outlets are no longer connected to the generator electronics. Due to, by way of illustration, faulty material, connections can be switched between a switched-off outlet and the generator electronic although the user had switched off this connection. This effect is caused, by way of illustration if the contact of the relay sticks or jams. The errors that the relay coil is interrupted or has a short circuit so that the contact can no longer close is less problematic.
Relays have the characteristic that they need relatively much power in order to pick up contact. This power has to be supplied by the internal supply, usually by an “auxiliary power supply” for the electronic control unit of the high-frequency surgical device. The auxiliary power supply is relatively highly loaded thereby. Therefore, it is desirable to reduce the power intake of the relay.
DESCRIPTION OF THE INVENTION
The object of the present invention is to provide a high-frequency surgical device which meets the pertinent standards for electromagnetic devices such as IEC
601
or VDE
0750
without using a mains separation transformer for galvanic separation of the mains supply and the user unit. Moreover the object of the present invention is to design high-frequency surgical devices more safely and to reduce the power input which auxiliary power supply devices have to fulfill.
The present invention is based on the following understanding: practically every HF surgical device possesses a high-frequency output transformer for power adaptation between the power final stage and the cutting electrode. The transformer is usually operated with a frequency of 0.3 to 1 Mhz.
However, this high-frequency output transformer is not employed in the known HF surgery devices for galvanic separation between the mains supply circuit and the user unit.
An element of the present invention is that it was understood that this HF output transformer can be utilized between the (mains) supply voltage and the patient/user unit. In order to do so, the HF output is designed according to the necessary standards, in particular, regarding the isolation voltage and regarding the air gaps and leakage distances. In particular, a high-frequency transformer that meets the FFIEC
601
respectively VDE
0750
standards can be utilized.
In view of the fact that high-frequency output transformers can be operated with very high frequencies, namely usually 0.3 to 1 mhz, the high-frequency output transformer can be designed small, light and therefore relatively less expensive compared to conventional mains separation transformers or conventional separation transformers in combinational mains circuit units. The invented design not only reduces the costs but also reduces the weight and the overall size of the device.
The operation elements of the control electronics that the user can come into contact with are galvanically separated from the power unit. This galvanic separation, by way of illustration, can occur by means of the construction of the casing, the switches respectively keys employed or by means of transmitters or optoelectronic couplers. This measure permits using a simple universal mains circuit as the internal current supply unit. The measuring signals and also the HF power can be separated by means of greater insulation from the mains.
This embodiment has the advantage that practically no control signals have to be separated between the power unit and the control electronics. However, more attention must be paid to inserting the components in the casing because a comparatively a large leakage distance and air gap is required to the grounded casing.
Preferred is if the control electronics are provided with a separate mains supply circuit.
In order to supply the HF power amplifier with the required power, the “mains supply circuit” is provided with a universal rectifier and a controllable DC/DC converter. The DC/DC converter permits covering the whole mains supply voltage range of 100-240 V alternating voltage. Preferably the DC/DC converter has the property to draw an almost sinus-shaped current from the mains. Due to this, the voltage is less distorted and the RMS current load and therewith the losses in the mains lines are reduced compared to conventional rectifiers.
Furthermore, the present invention is based on the understanding that a sticking relay contact is the most dangerous kind of failure of the control means for the patient respectively for the user. Notably, this kind of failure can result in the energy being simultaneously applied to two outlets. The switching state of the relay is then safe for the persons concerned if the relay is open. Therefore, an element of the present invention is that the function monitoring device checks if the contacts of the relay are being opened.
In order to do so, the function monitoring device for high-voltage relays for surgical devices according to claim
6
requires the following elements:
a control logic for at least one relay,
a controllable voltage supply source,
an inductivity measuring switch, and
drive unit which is provided with at least one relay driver.
The following relay properties are utilized:
1. Relays need a great current in the coil only to switch on. As soon as the contact is closed, a much smaller holding current is needed in order to maintain the contact.
2. The relay coil excites a magnetic circle whose properties change when the relay armature is closed. By way of illustration, due to this the inductivity changes. By closing the relay armature, the connection inductivity increases.
Usu
Daners Felix
Kellenberger Konrad
Novak Pavel
Peffley Michael
St. Onge Steward Johnston & Reens LLC
Storz Endoskop GmbH
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