Abstract: The invention relates to a piezoelectric actuator having a multi-layered structure of piezo-layers in a piezo element and inner electrodes that are arranged between the piezo-layers. The electrodes are alternatively supplied with an electric voltage of a different polarity in the direction of the layer structure of the piezoelectric element. The alternate lateral contacting of the inner electrodes is achieved via outer electrodes and/or a baked base metallic coating of the lateral surfaces. The respective outer electrodes include a bending coil which is wound from a contactable material. During baking of the base metallic coating the contactable material is applied together with at least parts of the bending coil to the coating in a conductive manner. A flexible sheet metal part that has first been provided with cut sections and/or pre-stamped sections can also be used as an outer electrode.

Abstract: The invention relates to a method for producing a piezoelectric actuator in which a metallization paste is applied to a sintered piezoelectric stack and a flexible metal electrode is arranged on top of the paste. In a subsequent baking or firing step, a base metallic coating is formed from the metallization paste, whereby the base coating is permanently connected to the piezoelectric stack and to the flexible metal electrode. Alternatively, the metallization paste can be applied to a green body which is subsequently sintered so that a first layer of a base metallic coating is formed in the sintering step. A metallization paste is applied to the first layer in a similar manner and a flexible metal electrode is arranged thereon, whereby the metal electrode becomes fixed during a second baking step.

Abstract: A separating device which utilizes a centrifuge which is driven by a motor for processing liquids enriched with solids by forcing the solids out of the liquid against a peripheral centrifuge wall as a consequence of centrifugal force characterized that a collecting vessel is the centrifuged container. The collecting vessel or centrifuge chamber has a plurality of axially spaced partitions with concentrically arranged openings to form axially spaced chambers which will collect the solids separated from the liquid as the liquid is discharged from the device. In one embodiment, the collecting vessel and centrifuge chamber are a single molded member. In another embodiment, there are two parts, with one being a container-like part receiving an insert having the parititons.

Abstract: A method and apparatus for cleaning, disinfecting, and sterilizing medical instrument with a sequence of method steps performed in a single apparatus. The method steps include precleaning the instruments in a container containing a first fluid bath subjected to ultrasonic energy, subsequently emptying the first fluid bath from the container and replacing it with a second fluid bath containing a cleaning agent and a sodium chloride, fine cleaning and disinfecting the instruments by subjecting the second bath to ultrasonic energy and circulating the second bath through an electrolytic cell having a voltage applied to the electrodes to create anotic oxidation, then emptying the second bath and replacing it with a rinse bath, rinsing instruments while subjecting the rinse bath to an ultrasonic energy and circulating the bath through the electrolytic cell subsequently emptying the rinse bath, and drying the instruments by means of heated air.

Abstract: A percussion instrument suitable for use in dental practice for determining the degree of looseness of teeth has a movably seated ram which is accelerated to a defined velocity by an electromagnetic drive means and is subsequently moved toward a test subject (such as a tooth) in free flight. The electromagnetic means also controls return of the ram to a rest position. The ram is comprised of a non-magnetic section and a section of low magnetic retentivity passing through a magnetic coil. Control electronics supplies current pulses to the coil. The velocity of the ram is detected by a measuring and evaluation unit and is maintained at a constant value after a comparison of a rated value with the actual velocity value. The current feed to the coil is discontinued when the rated velocity is reached.

Abstract: Long-term lubrication of highly loaded lubricating areas or surfaces, such as in very high speed medical and/or dental equipment, is obtained by applying a synthetic film, for example composed of poly(fluoroacrylic acid methyl ester) onto the sliding/moving surfaces, along with a polar oil having high lubricity. Anti-microbial agents can be added to the synthetic film. A pre-coat of molybdenum sulfide (MoS.sub.2) can be provided for the synthetic film. Stationary surface abutting the sliding/moving surfaces, such as cages for ball-bearings, preferably composed of a phenol resin, can function as a reservoir for the anti-microbial agents and the oil.

Abstract: A device which enables a rapid sterilization of one or more medical and dental objects characterized by a first chamber for containing the objects to be sterilized, a second chamber connected to the first chamber and having a smaller volume than the first chamber for receiving a liquid reaction fluid and positioning the fluid in an area of high energy density from a source of radiation such as infrared radiation or microwave radiation so that the object is vaporized and the vaporized gases of the reaction agent flow into the first chamber to sterilize the objects.

Abstract: A control installation for a dental apparatus which has at least one part capable of being moved to a selected position of a plurality of positions characterized by the control installation including a drive motor for moving the part to the selected position, a clock pulse generator coupled to the drive motor creating a pulse received by a pulse counter, a read-only memory producing a nominal or reference value indication, a comparator comparing the nominal value indication with the indication of the counted pulses to produce an error signal which is applied to a switching amplifier and then to the drive motor so that the operation of the drive motor depends on the presence of the error signal with the direction of rotation of the drive motor depending upon the operational polarity of the error signal.

Abstract: A hand-held instrument is illustrated wherein a counting cycle may be initiated by pressing the active electrode against a tooth to be examined. A digital to analog converter controls a battery operated current source to supply stimulating current pulses whose intensity is linearly increased in steps at the counting rate, independently of the electrical resistance presented by the external current flow path. The counter controls an indicator which displays the successive output current values, and displays the last reading for a predetermined time interval at the end of the counting cycle.

Abstract: An electric fluid heating device for heating comparatively small amounts of a fluid mdium, particularly for dental purposes, is characterized in that an operable controllable semiconductor, such as a transistor, is used as the heating element. The fluid heating device includes a metallic casing provided with a fluid heating chamber having a fluid inlet and outlet. The semiconductor is seated in a recess in the casing in heat exchange relation with the chamber. A temperature responsive control circuit including a PTC resistor in heat exchange relationship with the chamber is provided for regulating the current flowing through the semiconductor and thus the heat output thereof. The casing is made in two parts to permit a damaged smiconductor to be easily removed and replaced.

Abstract: A dental installation for at least one dental handpiece having a compressed air motor drive which is supplied from a compressed air source through a compressed air conduit, and whose rotational speed is variable by means of a control valve controlling the compressed air through the intermediary of a pneumatic installation which, preferably, is constructed in the shape of a foot or pedal switch. In an installation of the above-mentioned type, by means of which there is achievable a technical operational simplification, in addition to one or more handpieces having compressed air motor drives, there is also provided a further handpiece with an electric motor drive. In particular, it becomes feasible to effect a subsequent equipping of a purely pneumatically designed dental apparatus, which only incorporates handpieces having pneumatic drives, with a handpiece having an electric motor drive, without necessitating any significant tampering with the apparatus.

Abstract: A dental apparatus including a plurality of handpieces, each having associated therewith an electrical appliance such as, for example, a miniature drive motor, a generator for generating HF-oscillations, or an electrical valve for controlling the airflow of a turbine, whose operative condition (rotational speed, power output or valve flow-section) is variable through a change in the operating voltage by means of an adjusting element.