Electric lamp and discharge devices: systems – Current and/or voltage regulation
Patent
1989-06-06
1991-01-29
LaRoche, Eugene R.
Electric lamp and discharge devices: systems
Current and/or voltage regulation
315362, 315219, 323904, H05B 3702
Patent
active
049889249
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a circuit arrangement for controlling the brightness of a lamp according to the preamble of claim 1.
It is already known to control the brightness of a lamp in a light connected to a mains alternating voltage by touching an electrically conduCtive part of the light or of the lamp serving as a sensor (German periodical "Funk-Technik" [Radio Technology], Volume 37, Issue No. 5, 1982, page 192). Upon a first short touching of the sensor the lamp is switched on. When the sensor is being touched for a longer time, the brightness of the lamp, if required, can be modified. The lamp is switched off as the sensor is shortly touched a second time. Such known circuit arrangement comprises a lamp which is connected to a mains alternating voltage by means of a triac. A control unit, to which the sensor is connected, supplies a brightness signal to the triac. With the brightness signal the triac is switched on, switched off, or conductively controlled according to the desired brightness of the lamp. The brightness control of the lamp is thereby achieved according to a phase control which is controlled by the momentary value of the brightness signal.
For a low voltage lamp such as e.g. a halogen lamp, such known circuit arrangement is not provided for and not suited, either, because a low voltage source would be required for its operation. Particularly when using a conventional transformer for generating the required low voltage source, such circuit arrangement would require high expenditure and a large volume.
It is therefore the object of this invention to provide a circuit arrangement for controlling the brightness of a lamp, which arrangement is suitable for low voltage lamps and which requires low expenditure and particularly a small volume only.
According to the present invention this object is achieved in a circuit arrangement of the above-described kind by the features recited in the characterizing clause of claim 1.
The circuit arrangement according to the invention has the advantage that, particularly by using the transformer circuit, it is small in size and requires low costs only.
Advantageous further developments of the invention are shown in the claims 1 to 6.
An embodiment of the circuit arrangement according to the invention is described in detail hereinafter, reference being had the accompanying drawing in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of the circuit arrangement;
FIG. 2 is a simplified circuit diagram of the circuit arrangement; and
FIG. 3 shows time diagrams of signals at different locations of the circuit arrangement.
In the circuit arrangement shown in FIG. 1 a mains alternating voltage N of e.g. 220 V is supplied via a fuse SI to a rectifier GL which is designed particularly as a full-wave rectifier. The mains alternating voltage N is supplied via a phase connection PH and a neutral conductor NU. The rectifier GL rectifies the mains alternating voltage N and generates a first direct voltage G1, which is supplied to a transformer circuit which is designed as a half-bridge transformer and comprises a primary section P and a secondary section S. The primary section P has a primary winding PW which is magnetically coupled to the secondary winding SW of the secondary section S. A low voltage lamp L, particularly a halogen lamp, is connected to the secondary winding SW. Said lamp L lightens as soon as an appropriate voltage is induced in the secondary winding SW and a current I flows through the lamp.
The primary section P is controlled by a control unit ST, to which a sensor SE is connected. Such a control unit ST is commonly known and commercially available for example under the trade name S 576A (Siemens). The sensor SE is preferably connected with the secondary section S and arranged on the light. As an operating person BP touches the sensor SE, a small current S1 for example of 200 .mu.A flows from the rectifier GL via the resistors R3, R2, R1, the lamp L and the operating person BP. A voltage drop at the resistor R2 is evaluated
REFERENCES:
patent: 4168453 (1979-09-01), Gerhard
patent: 4250432 (1981-02-01), Kohler
patent: 4379254 (1983-04-01), Hurban
patent: 4663570 (1987-05-01), Luchaco
Funk-Technik 37 (1982), Heft 5, p. 192.
LaRoche Eugene R.
Zarabian Amir
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