Koninklijke Philips Corporation N.v.

Jacob Dijkstra

Timothy Van Der Graaf

Wilhelmus Gerardus Maria Ettes

Geert-Jan Darwinkel

Petrus Johannes Bremer

Schelte Heeringa

Harko Jan Taekema

Wilhelmus Ettes

Pawel Leshem

Harry Marinus

Johannes Albert Frankena

Einte Holwerda

Jan Buffinga

Wilhelmina Johanna Gerarda Van De Wassenberg

Gaatze Bareld Bosma

An air purification system is provided which includes measurement of a concentration of a target pollutant within the air. A gas sensor is used for sensing a concentration of the pollutant (although it will detect other pollutants as well due to cross-sensitivity). A filter is provided which selectively removes the target pollutant while having a significantly smaller effect in reducing other pollutants to which the sensor is cross-sensitive. A gas sensor response is obtained before filtering, a gas sensor response after filtering, and the sensitivity characteristics of the gas sensor to the pollutant are processed, thereby to determine a gas concentration of the pollutant in the air before filtering. In this way, the concentration measurement is better than a direct measurement with the gas sensor as a result of a low selectivity of the gas sensor.

System and method for measuring a concentration of a pollutant within a gas

The present invention relates to a humidifier and a method of monitoring the water level in the humidifier, the method comprising the steps of: detecting the temperature at the air outlet of the humidifier and generating temperature signals indicating the temperature thereof (); determining the water level in the humidifier according to the generated temperature signals (). The water level in the humidifier can be monitored using a rather simple structure yielding a high accuracy.

Humidifier and a method of monitoring the water level in the humidifier

A wake-up lighting device is described, comprising a gas discharge lamp () and a lamp driver () comprising a power source () capable of generating spaced-apart current bursts () of alternating lamp current (I). The wake-up lighting device is capable of operating in an off-mode in which no lamp current is generated, and is adapted to switch from its off-mode to a wake-up mode in which the power source () operates to:&#x2014;initially generate an alternating lamp current (I) with a minimum duty cycle value (&#x394;T) and a reduced current amplitude (IR) close to zero;&#x2014;subsequently gradually increase the current amplitude while keeping the duty cycle (&#x394;) constant at the minimum duty cycle value (&#x394;T), until the current amplitude reaches a nominal current amplitude (IM);&#x2014;subsequently gradually increase the duty cycle (&#x394;) while keeping the current amplitude constant at the nominal current amplitude (IM).

Variable light-level production using different dimming modes for different light-output ranges

A compact gas discharge lamp () comprising four (or more) interconnected tube segments () is provided with an external electrode () that extends at least throughout the length of the tube segments and that is in contact with all tube segments. Several embodiments of the external electrode are disclosed. The external electrode is preferably connected to a node (C) midway between the lamp electrodes, to which end a capacitive divider () is arranged in parallel with the lamp.

Dimmable light generating device

A driver for driving a gas discharge lamp includes an inductive ballast implemented as auto-transformer having a central tap, connected between one output terminal and a first input terminal, and a triac connected between a second output terminal and a second input terminal. The central tap of the ballast is connected, via a capacitor, to the second output terminal. A control unit has a sense input for sensing the phase of an input voltage at the first input terminal, and is adapted to trigger the triac at a predetermined phase (&#x3a6;) after a zero-crossing of the input voltage, the predetermined phase (&#x3a6;) being in the range of &#x394;&#x3a6;+10&#xb0; to &#x394;&#x3a6;+15&#xb0;, &#x394;&#x3a6; being the nominal phase lag of the lamp current with respect to the input voltage.

Circuit arrangement

A motor speed control for controlling the speed of an electric induction motor by modulating the amplitude and frequency of the driving voltage. When the load increases the speed control controls the speed so as to be relatively constant with respect to the frequency of the driving voltage. Preferably, the speed control controls the amplitude of the driving voltage in proportion to the square of the frequency.

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Drachten, Netherlands

Jacob Dijkstra