U.S. Philips Corporation

Koninklijke Philips Corporation N.v.

North American Philips Corporation

Klaas Vegter

Petrus H Antonis

Pieter Jan Van Der Zaag

Johan Paul Marie Gerard Linnartz

Nebojsa Fisekovic

Pieter J Van Der Valk

Sel-Brian Colak

Controlling a lighting system, which comprises a controller (), lighting units (), and a sensing device. Each lighting unit comprises a lighting source () and a modulated light source (). A single light source may be used to function as both the lighting source and the modulated light source. Each modulated light source emits uniquely modulated light. A radiation pattern of each modulated light source coincides substantially with a radiation pattern of a lighting source of the same lighting unit. The sensing device is suitable to sense modulated light in a viewing area. Lighting units from which the sensing device senses modulated light are identified from the modulation of that modulated light. The sensing device measures the intensity of the modulated light from the identified lighting unit. The lighting sources are controlled dependent on control data which comprises measuring values of measured light intensities.

Illumination control

An illumination unit including an electrodeless low-pressure discharge lamp (20) and a supply device (50). The lamp has a discharge vessel (30) which encloses in a gastight manner a discharge space (31) which is provided with an ionizable filling. The lamp (20) further has a coil (40) provided with a winding (42) around a sintered core (41) of polycrystalline ferrite material, which winding (42) is connected to the supply device (50). The coil (40) is capable of inducing a high-frequency magnetic field which maintains a discharge in the discharge space (31). The losses in the core (41), when measured at room temperature in a magnetic field with a frequency of 3 MHz and a magnetic flux density of 10 mT, amount to at most 150 mW/cm.sup.3. This has the advantage that the lamp (20) ignites comparatively quickly and loads the supply device (50) comparatively weakly during ignition. The supply device (50) as a result can have a comparatively long useful life.

Illumination unit, electrodeless low-pressure discharge lamp, and coil

The invention relates to a circuit arrangement for operating a lamp (La), provided with

Discharge lamp control circuit using a luminous flux table

An electrodeless low-pressure discharge lamp (10) according to the invention is provided with a radiation-transmitting discharge vessel (11) which encloses a discharge space (14) containing an ionizable filling in a gastight manner. The lamp (10) is in addition provided with a first and a second winding (20, 23) for conducting a high-frequency current during operation. The first winding (20) extends along a longitudinal axis (29) in a cavity (28) surrounded by the discharge vessel (11). The second winding (23) is arranged along the longitudinal axis (29) in the extended direction of the first winding (20) outside the cavity (18) surrounded by the discharge vessel (11). During operation, the currents in the first and second windings (20, 23) have the same tangential direction relative to the longitudinal axis (29). The lamp causes comparatively little magnetic interference, while it is avoided that the second winding (23) hampers lamp ignition or causes an unstable lamp operation.

Electrodeless low-pressure discharge lamp, and lighting unit provided

A low pressure gas discharge lamp (such as a fluorescent lamp) which includes a wire mesh grid disposed within the lamp envelope so as to intercept the electrons flowing between the lamp electrodes. A lead wire extends from the grid to the outside of the lamp envelope, when the grid is provided with a negative voltage with respect to the surrounding plasma the lamp may switched off. The grid controlled lamp eliminates the need for a solid state power switch in the lamp driving circuitry. As such, the lamp current flows only through the lamp not through the electronic ballast/lamp driving circuitry. With the lamp current removed from the ballast circuitry, power dissipation problems in the driver circuitry is eliminated. The grid controlled lamp design greatly facilitates circuit design.

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Eindhoven, Netherlands

Klaas Vegter