U.S. Philips Corporation

Koninklijke Philips Corporation N.v.

Hans Steinbusch

Matthias Wendt

Christian Reichinger

Gerhard Diefenbach

Gunter Doring

Wolfgang M Radziwill

Heinz Willi Van Der Broeck

A starting-process controller for starting a piezomotor, having a voltage-controlled oscillator, a power output stage, and a resonant converter. The oscillator generates the control signals required for the power output stage and the resonance converter converts the stepped output voltage from the power output stage into a sinusoidal voltage at the output. The resonance converter drives the piezomotor with the voltage. The motor current that flows when the piezomotor is driven is measured and compared with the phase of the drive voltage in a phase comparator. The comparison output signal is a measure of the phase difference at the time between current and voltage. A phase-locked loop filter smoothes the phase-difference signal for controling the oscillator. The controller includes a start-assisting circuit element that fixes the output voltage from the phase-locked loop filter at start-up and thus applies a constant voltage to the input of the voltage-controlled oscillator.

Starting-process controller for starting a piezomotor

A piezoelectric driving device and a regulation method for a piezoelectric driving device are proposed. Piezoelectric driving devices known so far show a characteristic with which the electric power applied to the motor drops when the load increases. This behavior, which leads to a strong reduction of the range of use of such motors, is counteracted by predefining the amplitude of the excitation voltage so that the effective power does not drop with increasing load. For this purpose the electrical effective power is determined from the excitation voltage and the current flowing through the piezoelectric resonator. Alternatively, with a predefined fixed phase angle between excitation voltage and current a regulation may also be effected in the way that the current is kept to the constant value. A further aspect of the invention relates to a unit for limiting the current flowing through the piezoelectric resonator, so as to avoid this component being damaged.

Piezoelectric driving device and a regulation method for a piezoelectric driving device

A method of controlling a circuit arrangement for an AC voltage supply of a plasma display panel, the circuit arrangement comprising at least a transistor bridge constituted by the bridge transistors (T, T, T, T), an input voltage (U), a capacitor (Cp) of the plasma cell and a charging circuit comprising an auxiliary voltage (Uh), a first auxiliary transistor (T) and a first coil (L) and at the beginning of the charging operation the first auxiliary transistor (T) is turned on, characterized in that once the first auxiliary transistor (T) has been turned on, the second bridge transistor (T) of the half bridge continues to be turned on for a delay time tv and is turned off after the delay time tv has elapsed.

Method of controlling a circuit arrangement for the ac power supply of a plasma display panel

A circuit arrangement for powering an electric motor having at least three windings from a direct voltage source via a commutation circuit which, for each winding terminal of the electric motor, comprises a commutation branch including a first and a second switching element by which the relevant winding terminals can be connected selectively to a first terminal of the direct voltage source or, via a measurement impedance, to a second terminal of the direct voltage source. A ring counter device periodically changes over the switching elements of the commutation circuit in accordance with a signal series which is cycled through the ring counter device under control of a clock signal, one period of the ring counter device corresponding to one complete cycle of the signal series through the ring counter device. A clock frequency generating stage supplies the clock signal whose clock frequency is dependent on the measurement voltage. A motor-current dependent commutation which operates reliably for all operating conditions of the motor, particularly all speeds, using a circuit of low complexity, is obtained in that a sample and hold circuit has an input coupled to the measurement impedance in order to sample a measurement voltage appearing across the measurement impedance and in that the ring counter device, in each of its periods, controls the sample and hold circuit so as to acquire a sampled value of the measurement voltage at a presettable instant outside the time interval for the change-over of the switching elements of the commutation circuit.

Circuit arrangement for powering an electric motor

An electromechanical device has a coil configuration comprising an insulating substrate (30) carrying a first group of 12 series-connected spiral conductor patterns (21a-21m) and a second group of 12 series-connected spiral conductor patterns (22a-22m). Some of the conductor patterns (21a, 22a, 21d, 22d, 21e, 22e, 21i, 22i, 21j, 22j, 21m and 22m) are disposed on the upper side of the substrate (30). Other ones of the conductor patterns (21b, 22b, 21c, 22c, 21f, 22f, 21h, 22h, 21k, 22k, 21l and 22l) are disposed on the underside of the substrate (30). The conductor patterns on both sides of the substrate (30) are electrically interconnected by means of plated-through connections (40). The first group is in arranged in parallel with the second group by means of common connection electrodes (51 and 52). The conductor patterns (21a-21m) of the first group and the conductor patterns (22a-22m) of the second group are carried by the same substrate (30).

Electromechanical device, coil configuration for the electromechanical

A DC motor is commutated by magnetically controllable electronic switches in the form of integrated semiconductor circuits. Each switch comprises a first switching path between a first input terminal and an output terminal and a second switching path between a second input terminal and the output terminal. The two switching paths are controlled by the magnetic field of the rotor such that either the one or the other switching path is closed and that both switching paths are open in positions intermediate between these two positions.

DC motor with electronic commutation circuit

A magnetically controllable electronic switch in the form of an integrated semiconductor circuit comprises a first switching path between a first input terminal and an output terminal and a second switching path between a second input terminal and the output terminal. The two switching paths are controllable by a magnetic field in such a way that either the one or the other switching path is closed and the two switching paths are open in the transition range between these two modes. Such a switch is particularly suitable for use as an electronic commutator for small electric motors.

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Landgraaf, Netherlands

Hans Steinbusch