LIGHTING SYSTEM, LAMP, REMOTE CONTROL OR ADDITIONAL ELEMENT AS PART OF THIS SYSTEM

The invention relates to a lighting system, comprising a group of lamps suitable for placing in for instance a Christmas tree, wherein each lamp is provided with a light source, a power source and a receiver for electromagnetic or acoustic signals, in addition to a remote control provided with transmitting means for generating electromagnetic or acoustic signals.

A lighting system of this type is known from DE 41 20 849. This relates to Christmas tree lighting wherein each Christmas tree lamp is equipped with a photocell and wherein the photocells are controlled simultaneously using a transmitter which generates light signals.

A drawback of the known system is that signals generated by a remote control of one system can operate the lamps of another system. It is of course possible to produce different types of lamp with associated remote controls, although logistically this is not very attractive.

The present invention obviates this drawback and has the feature that the lighting system also comprises an additional element which is placed in a situation of use at least substantially centrally between the lamps, and which is suitable for generating an additional signal which can be received by the receivers. It is then sufficient to produce different types of additional element.

A favourable embodiment has the feature that the transmitting means are adapted to generate an RF signal, that the receivers comprise RF receivers, each provided with a mixer stage, and that the additional element comprises an RF oscillator for generating an RF signal. The RF signal generated by the transmitting means and the RF signal generated by the additional element preferably have different frequencies so that the receivers then in fact have to process a relatively low-frequency mixed signal obtained from the RF signal of the remote control and the RF signal of the additional element, whereby the sensitivity of the receivers can increase. It is of course also possible to provide each receiver with an oscillator, although the lighting system thereby becomes relatively expensive. Nor is it then possible to preclude interference between the different receivers.

A further favourable embodiment has the feature that the receivers are provided with a filter for allowing passage of signals with a frequency corresponding

to the difference in frequency between the RF signal generated by the transmitting means and the RF signal generated by the additional element.

A further favourable embodiment has the feature that the receivers are reflex receivers. In a per se known reflex receiver the mixer stage and/or the RF amplifier are also used to amplify the detected low-frequency signal so that the receiver can be realized with a minimum number of amplifier elements. The difference in frequency between the RF signal generated by the transmitting means and the RF signal generated by the additional element here preferably amounts to a minimum of 300 kHz and a maximum of 30 MHz. A reflex receiver for this frequency range can be realized in simple manner and good and inexpensive filters are available.

A favourable alternative embodiment of the invention has the feature that the transmitting means are adapted to generate an RF signal, that the receivers comprise acoustic receivers and that the additional element comprises an RF receiver and an acoustic transmitter. The additional element can then be placed favourably so that the RF signal transmitted by the remote control can always be received, even at low transmitting power. A low power is also sufficient for the signal transmitted by the acoustic transmitter, because the lamps are all situated in the immediate vicinity of the additional element.

A further favourable embodiment has the feature that the RF receiver is a superregenerative receiver. Such a receiver is inexpensive and sensitive, while the power consumption is also low.

A further alternative embodiment has the feature that the transmitting means are adapted to generate an optical signal, that the receivers comprise acoustic receivers and that the additional element comprises an optical receiver and an acoustic transmitter. The additional element can then be placed favourably so that the optical signal transmitted by the remote control can always be received, even at low transmitting power. A low power is also sufficient for the signal transmitted by the acoustic transmitter, because the lamps are all situated in the immediate vicinity of the additional element. A further alternative embodiment has the feature that the transmitting means are adapted to generate an optical signal, that the receivers comprise RF receivers and that the additional element comprises an optical receiver and an RF transmitter. The additional element can then be placed favourably so that the optical signal transmitted by the remote control can always be received, even at low transmitting power. A low power is also sufficient for the signal transmitted by the RF transmitter,

while the sensitivity of the RF receivers can be low because the lamps are all situated in the immediate vicinity of the additional element.

The invention also relates to a lamp, a remote control or an additional element as part of a lighting system as specified in the foregoing paragraphs.

The invention will now be further elucidated on the basis of the following figures, wherein:

Fig. 1 shows schematically a possible embodiment of a lighting system according to the invention;

Fig. 2 shows schematically a possible embodiment of a Christmas tree lamp according to the invention;

Fig. 3 shows schematically an alternative embodiment of a Christmas tree lamp according to the invention; Fig. 4 shows schematically a further alternative embodiment of a Christmas tree lamp according to the invention;

Fig. 5 shows schematically a possible embodiment of an additional element;

Fig. 6 shows schematically an alternative embodiment of an additional element; Fig. 7A shows schematically a possible embodiment of an RF receiver;

Fig. 7B shows schematically an alternative embodiment of an RF receiver;

Fig. 8 shows schematically a possible embodiment of a reflex receiver with only one transistor.

Fig. 1 shows schematically a possible embodiment of a lighting system according to the invention, consisting of a number of lamps 1 which can be attached in a Christmas tree 2, and a remote control 3 with which the light intensity of the lamps can be controlled. Remote control 3 is provided with pushbuttons 4a,4b for respectively switching on and switching off lamps 1 or for respectively increasing and decreasing the intensity of lamps 1. The lighting system operates wirelessly. Remote control 3 is therefore provided with a transmitter 7 and an antenna 6, or with a light- emitting diode or with an acoustic emitter for controlling lamps 1. According to the invention the lighting system is moreover provided with an additional element 7 which supports the reception of signals transmitted by remote control 3. This is

useful because the distance between Christmas tree 2 and remote control 3 can be great, while the distance between additional element 7 and lamps 1 is small.

Fig. 2 shows schematically a possible embodiment of a Christmas tree lamp 1 according to the invention consisting of a tubular housing 8 with a top 9 which has the form of a candle flame, and a dish 10 to which via a ball joint 11 a clamp 12 is fixed with which Christmas tree lamp 1 can be attached to a branch. Accommodated in housing 8 is a receiver 13 provided with an antenna 14 which can receive RF control signals from remote control 3 as shown in Fig. 1, and which can switch on a light-emitting diode 15, wherein energy is supplied by two batteries 16a, 16b accommodated in dish 10. Top 9 is manufactured from a transparent plastic, for instance polycarbonate, in which small metal particles or air bubbles 17 are embedded, which has the result that light from light-emitting diode 15 is diffused, whereby substantially the whole volume of top 9 appears to radiate light.

Fig. 3 shows schematically an alternative embodiment of a Christmas tree lamp 1 according to the invention, consisting of a tubular housing 8 with a top 9 which has the form of a candle flame, and a dish 10 to which via a ball joint 11 a clamp 12 is fixed with which Christmas tree lamp 1 can be attached to a branch. Accommodated in housing 8 is a receiver 13 provided with a photodiode 18 which can receive optical control signals from remote control 3 as shown in Fig. 1, and which can switch on a light-emitting diode 15, wherein energy is supplied by two batteries 16a, 16b accommodated in dish 10. Top 9 is manufactured from a transparent plastic, for instance polycarbonate, in which small metal particles or air bubbles 17 are embedded, which has the result that light from light-emitting diode 15 is diffused, whereby substantially the whole volume of top 9 appears to radiate light. Fig. 4 shows schematically a further alternative embodiment of a Christmas tree lamp 1 according to the invention, consisting of a tubular housing 8 with a top 9 which has the form of a candle flame, and a dish 10 to which via a bail joint 11 a clamp 12 is fixed with which Christmas tree lamp 1 can be attached to a branch. Accommodated in housing 8 is a receiver 13 provided with a microphone 19 which can receive acoustic control signals from remote control 3 as shown in Fig. 1 , and which can switch on a light-emitting diode 15, wherein energy is supplied by two batteries 16a, 16b accommodated in dish 10. Top 9 is manufactured from a transparent plastic, for instance polycarbonate, in which small metal particles or air bubbles 17 are embedded, which has the result that light from light-emitting diode 15 is diffused, whereby substantially the whole volume of top 9 appears to radiate light.

Fig. 5 shows schematically a possible embodiment of an additional element 7, consisting of a tubular housing 20 and a dish 21 in which two batteries 16a, 16b are accommodated and to which via a ball joint 11 a clamp 12 is fixed with which Christmas tree lamp 1 can be attached to a branch. Received in housing 20 is a receiver 22, in addition to an amplifier 23 and a transmitter 24. Receiver 22 receives signals from remote control 3, amplifier 23 amplifies these signals and transmitter 24 retransmits these signals in a manner such that Christmas tree lamps 1 can receive them. Receiver 22 can here be adapted for instance to receive RF signals, while transmitter 24 is adapted to generate acoustic signals, although other combinations can be envisaged subject to the circumstances. In the above mentioned combination receiver 22 can be formed by a superregenerative receiver, while transmitter 24 can consist of a simple ultrasonic emitter. Christmas tree lamps 1 can then be embodied with a microphone as described with reference to Fig. 4.

Fig. 6 shows schematically an alternative embodiment of an additional element 7, consisting of a tubular housing 20 and a dish 21 in which two batteries 16a,16b are accommodated and to which via a ball joint 11 a clamp 12 is fixed with which Christmas tree lamp 1 can be attached to a branch. Accommodated in housing 20 is an RF oscillator 25 which is connected to an antenna 26. This alternative embodiment can advantageously be utilized when remote control 3 transmits RF signals. RF oscillator 25 has a frequency differing by for instance 10 MHz from the RF frequency transmitted by remote control 3. The first stage of the receivers of lamps 1 is then a mixer stage which generates a signal of 10 MHz when remote control 3 is activated. The receivers are hereby in fact superheterodyne receivers, wherein RF oscillator 25 forms the oscillator for all receivers. This has the result that the receivers can be manufactured more simply and more cheaply. Furthermore, different frequencies can be selected for the combination of the remote control and the additional element, whereby a remote control cannot interfere with another nearby Christmas tree lighting.

Fig. 7A shows schematically a possible embodiment of an RF receiver 13 for a Christmas tree lamp 1 as can be used in combination with an additional element as according to Fig. 6. Receiver 13 has a per se known mixer stage 27 which is connected to antenna 14 and in which RF signals from remote control 3 and RF oscillator 25 are mixed. The mixed signal is then passed through a per se known filter stage 28, amplified in amplifier stage 29 and rectified in detector stage 30. This

signal is subsequently amplified in a low-frequency amplifier 31 and then used to switch light-emitting diode 15 on or off in a per se known manner.

Fig. 7B shows schematically an alternative embodiment of an RF receiver 13 for a Christmas tree lamp 1 as can be used in combination with an additional element as according to Fig. 6. Receiver 13 is of the reflex type and has a per se known mixer stage 27 which is connected to antenna 14 and in which RF signals from remote control 3 and RF oscillator 25 are mixed. The mixed signal is then passed through a per se known filter stage 28, amplified in amplifier stage 29 and rectified in detector stage 30. In accordance with the reflex principle, this low- frequency signal is fed back to mixer stage 27 or to amplifier stage 29 in order to be amplified. This amplified low-frequency signal is subsequently used to switch light- emitting diode 15 on or off in a per se known manner. If the RF signal transmitted by remote control 3 is sufficiently strong, amplifier stage 29 can generally then be omitted. Fig. 8 shows schematically a possible embodiment of a reflex receiver 13 with only one transistor. The signal received by antenna 14 is fed via a transformer to mixer stage 27 consisting of one transistor. Incorporated in the collector line of this transistor is a filter 28, the output signal of which is fed via a transformer to detector 30. The thus obtained low-frequency signal is then fed back via a potentiometer 32 to the base of the transistor. The amplified low-frequency signal is taken off over a resistor 33 incorporated in the collector line.