The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 21, 2003
Filed:
Feb. 26, 2001
Jeppe Christian Bastholm, Sønderborg, DK;
Kjeld Kristiansen, Sønderborg, DK;
Linak A/S, Nordborg, DK;
Abstract
A power supply for DC motors, in particular for actuators for use in the adjustment of tables, beds and the like, comprises a transformer (T ) with a rectifier (D -D ); and a buffer capacitor. The power supply comprises voltage limiting unit (Z ) coupled in parallel with the motor and connected to switch unit (Q ) so that the motor is connected on a first part of the sine half-waves, but is disconnected when the voltage determined for the voltage limiter is reached. This ensures a good mean voltage, and the voltage does not exceed an upper permissible value. This also means that the motor speed is more independent of the load, which is an advantage e.g. in case of height-adjustable tables. In an embodiment, the power supply comprises additional means for measuring the current power in the motor, and this measurement is used as a feedback for controlling the motor speed to keep the speed of the motor. Hereby, a constant motor speed is achieved for loads up to the maximum output of the transformer, and only then begins the speed to decrease. For example in case of height-adjustable tables, the user will see under normal conditions that the tabletop is raised and lowered at a constant speed.