Often, lamps with adjustable parameters are used for the illumination of buildings. These adjustable parameters include the selection of lamps which are to be switched on and the desired brightness of the lamps. Usually the lamps can be controlled by a switch near a door for switching the lamp on or off. The switch can be equipped with a dimmer for varying the brightness of the lamps.
Conductor rail systems are known, which permit positioning of lamps at any location along a conductor rail. The conductor rail consists of a U-profile, which can be mounted in or on the ceiling of a room. Insulated conductors paths are provided along the conductor rail on the inside of the U-profile. Each lamp has an adapter for attaching the lamp to the conductor rail system. The adapter has built-in contact pads to provide electrical connection to the electrical conductors of the conductor rail. The advantage of such conductor rail systems is, that the lamp can easily be mounted at a desired position even by a person having no or little professional skill. A further advantage of the conductor rail systems is, that they can be pre-installed in new buildings, even if the use, the number, type and position of the lamps is still not determined. Conventional conductor rail systems of this type do not permit individual control of lamps. Therefore additional means have to be used to provide the lamps with information about the desired operational state.
To this end, it is known to transmit such information via radio frequency or infrared transmitters and receivers. Such transmission is interference prone. The transmission causes “electrical smog”, which may disturb other devices. Also the use of specific transmitter and receiver systems is expensive. If the information is transmitted by infrared radiation, other systems in the room may be disturbed.
It is known to transmit information combined with a power supply through cables passing through cable ducts. Cable ducts are fixedly installed tubes or profiles made of plastics. In these cable duct, a multitude of electric wires, data cables and other cables can be loosely guided. Integrated junctions are provided in the plastic tubes. With a suitable interface the energy and information can be taken from these junctions. The junctions are located at fixed predefined locations in the cable duct. Installing additional junctions requires a skilled person and is expensive.
A system with a conductor rail and a data line is known under the name EIB (European Installation Bus). This system is described among others in the paper “Tageslichtabhängige Beleuchtungssysteme auf der Basis von Installationsbussen” by P. T. Knoop, Fortschritt-Ber. VDI Reihe 6 Nr. 396 1998. In this system, each lamp of an installation is connected with the conductor rail and the data line through a junction. The junction has a data processing unit. The junctions are provided together with an information generator and a translator in an actuator. The actuator is rigidly connected to the conductor rail. Each actuator of the system has equality of access regarding the communication of the connected devices. Each connected device is transmitter and receiver of information, which communicate through a bus-system. There is no central control unit. Therefore, the system is suitable for nearly unlimited large applications, like the management of complex systems in a building. But the system is too expensive for many simple applications.
DE 38 12 465 C2 discloses the combination of simple conductor rails with data lines for the illumination engineering. The system has a central control unit, which takes over the control of the system (master-slave-system). The lamps can be connected to the power conductor rail through a simple choke and an adapter. The control data can be communicated to the lamps through the data line. This permits central adjustment, for example, of the brightness of the lamps.
In the prior art conductor rail system with data line, the data flow in the form of control commands from the central control unit to the lamps connected to the conductor rail system. A change of the operational state can only be achieved by a program or by an input to the control unit.