Field of the invention

The invention relates to a lighting system comprising a plurality of lamps arranged to transform electricity into a light beam having properties such as intensity, colour, colour temperature, direction and beam cone angle, and a light control means arranged to adjust said light beam properties.

Background of the invention

In existing lighting applications often a very wide illumination of the whole room is performed. But in many cases only a small part of the room needs to be illuminated, which is not energy efficient. In other light applications, a smoothly movable lightbeam is required, for instance in order to follow a person on a stage or in order to precicely move the lightbeam towards the required location. In existing light applications lightbeam position deviation is achieved in a mechanical way, which is not flexible and is vulnerable to mechanical failures. Also, the area that for instance one lamp with a movable lightbeam can reach is limited.

It is a goal of the invention to provide a more robust, energy efficient, easy to use and/or flexible lighting system.

Summary of the invention

According to the invention each lamp in the system comprises a plurality of light units, wherein said light units are arranged in an array, wherein the lightbeams of substantially each pair of adjacent light units in a lamp overlap each other, and wherein each lamp comprises a light control means which is arranged to adjust the intensity of each one of said plurality of light units individually, wherein said light control means is further arranged to maintain the total combined luminous flux incident of said plurality of light units in said lamp on a predefined imaginary flat surface substantially equal when adapting the intensity of the individual light units (such that the total illuminance of said imaginary surface would be substantially constant), and wherein each of said lamps comprises communication means, arranged to exchange instructions with the communication means of the other lamps in said system, such that said light control means in each lamp is arranged to maintain the total combined luminous flux incident of all light units in said system on a predefined imaginary flat surface substantially equal when adapting the intensity of the individual light units of said lamps. Preferably said light control means are arranged to adapt the intensity of the individual light units in all of said lamps by dimming and brightening such that the direction of the combined light beam of the light units that are switched on moves smoothly from a first direction to a second direction.

Through the interaction of the control means in each lamp, the combined light beam, at least at the location of incidence of the light beam, can be built up from partial light beams of more than one lamp, and the light beam can be easily and smoothly moved over large, in principle unlimited, distances. A smooth transition is obtained, which is very close to the effect that is experienced by a user when a lightbeam is moved by physically moving the spotlight.

Preferably the control means of each lamp of said system is arranged such, that said smooth movement of the direction of the combined light beam of the light units that are switched on moves from a first direction to a second direction, is achieved when said lamps are mounted in a predefined configuration. In an alternative preferred embodiment the control means of each lamp of said system is arranged to be adapted during a setup phase in dependence on the sequence or configuration in which the lamps are mounted.

In the preferred embodiment said communication means are preferably wireless communication means, such as radiofrequency wireless communication means and preferably said light units are LEDs.

Preferably said plurality of light units of each lamp are contained in a lamp housing and said lamp housing preferably comprises a standard lamp fitting.

In the preferred embodiment each lamp of said lighting system further comprises an ultrasonic transmitter arranged to transmit ultrasonic signals, an ultrasonic receiver arranged to receive reflected ultrasonic signals, and a processing means arranged to derive a time-of-flight signal representing the time differences between said transmitted and received ultrasonic signals and to send control signals to said light control means in dependence of said time-of-flight signal for adapting the light intensity of said individual light units. Preferably said ultrasonic receivers and transmitters are arranged such that at least the movement of an object in a plane substantially perpendicular to the ultrasonic beams can be detected and measured by each lamp, as explained in more detail below. In this manner the lamp system can be smoothly controlled by moving an object, such as a hand, through the adjacent ultrasonic beams.

Said processing means of each lamp are preferably arranged to perform a calibration procedure of said ultrasonic transmitters and/or receivers, when the lamps are in the mounted position, such that the areas, where said processing means respond to reflected signals from objects in said areas, of each lamp do not overlap.

Furthermore preferably said processing means of each lamp are arranged to perform a calibration procedure of said ultrasonic transmitters and/or receivers, when the lamps are in the mounted position, such that upon a predetermined difference in time-of- flight measurement between two neighbouring lamps, preferably upon a substantially equal difference in a multitude of such measurements over a predetermined amount of time, an indication thereof is stored, and said processing means are further arranged such that if an object is detected moving towards the location of said two neighbouring lamps a deviating light signal is emitted by said lamps. In this manner for instance a step in a walkway can be automatically detected and stored, and a person walking towards said step can be warned.

The lighting system further preferably comprises at least one ultrasonic transmitter for adapting the light intensity of said individual light units by using time-of-flight measurements in the Z-direction (being the lamp axes), as described herein, and/or by using one of the proposals for gesture control in the XY-plane (being the plane perpendicular to the lamp axis) as described herein. In particular gesture control in the XY-plane is well suited for control of the light beam direction and/or angle of the lighting system. In a preferred embodiment the lighting system further comprises a plurality of ultrasonic transmitters arranged to transmit ultrasonic signals; a plurality of ultrasonic receivers arranged to receive reflected ultrasonic signals; and a processing means arranged to send an ultrasonic pulse sequentially through each of said transmitters and to determine after each pulse is sent which ones of said receivers receive a reflected ultrasonic signal with an amplitude exceeding a predetermined threshold within a predetermined period, and to send control signals to said light control means in dependence of said determination. Preferably said ultrasonic transmitters are arranged such that the ultrasonic signals are transmitted within and parallel to the light beam of the lamps. Said ultrasonic transmitters and receivers are preferably arranged in an equilateral polygon or a circle. In the preferred embodiment said system comprises three of said transmitters and three of said receivers.

In another preferred embodiment the lighting system further comprises an ultrasonic transmitter arranged to transmit ultrasonic signals; an ultrasonic receiver arranged to receive reflected ultrasonic signals; wherein said ultrasonic transmitter and/or receiver are mounted on a rotatable carrier such that the beam of said transmitter and/or the reception cone of said receiver extend parallel to and at a distance from the axis of rotation, wherein driving means are present to rotate said carrier; and a processing means arranged to send an ultrasonic pulse repeatedly through said transmitter during rotation at a multitude of angular positions of said carrier and to determine after each pulse is sent if said receiver receives a reflected ultrasonic signal with an amplitude exceeding a predetermined threshold within a predetermined period, and to send control signals to said light control means in dependence of said determination. Preferably the axis of rotation of said rotatable carrier extends within, and parallel to, the light beam of the lamp. Said processing means is preferably arranged to send an ultrasonic pulse at least 3, preferably at least 6, more preferably at least 12 angular positions of said carrier.

The processing means is in the preferred embodiment further arranged to derive a time-of-flight signal representing the time differences between said transmitted and received ultrasonic signals and to send control signals to said light control means in dependence of said time-of-flight signal, as will be further explained below. This control mechanism provides a high resolution control, and is for instance very suitable for controlling light intensity, colour and/or colour temperature.

In yet another preferred embodiment the lighting system further comprises at least one ultrasonic transmitter arranged to transmit ultrasonic signals; a plurality of spaced apart ultrasonic receivers arranged to receive reflected ultrasonic signals; and a processing means arranged to determine for each of said receivers time-of-flight signals representing the time differences between said transmitted signals from said at least one transmitter and the associated received reflected ultrasonic signals from said receiver, and to send control signals to said light control means in dependence of the combination of said time-of-flight signals for each of said receivers. Preferably said combination of said time-of-flight signals for each of said receivers is a function of said time-of-flight signals defining the location of an object reflecting said ultrasonic signals in a two-dimensional plane or a three-dimensional space within the beams of said transmitters and receivers.

All of the above-mentioned aspects of the invention provide, in a very efficient, cheap and reliable manner, the possibility to control the light system by hand gestures in directions substantially perpendicular to the axis of the ultrasound beams. If a reflecting object (such as a hand) is present in one of the beams, the position of the object in said directions can continuously be determined, and control of the of the light beam direction of the lighting system can be achieved thereby.

Said processing means is preferably arranged to analyse the dynamic behaviour of said time-of-flight signals and to send control signals to said light control means in dependence of said dynamic behaviour.

In the preferred embodiments the processing means are arranged to derive a time-of- flight signal representing the time differences between said transmitted and received ultrasonic signals and to send control signals, for instance binary code, to said light control means in dependence of said time-of-flight signal. Thereby a user of the system can further adjust lamp properties such as intensity or colour by moving an object, such as his hand, in the direction of the axis of the ultrasonic beam. The ultrasonic transmitters may for instance emit sound at a frequency of 40 kHz. Although alternatives to the use of ultrasonic transmitters/receivers, such as for instance infrared or radar transmitters/receivers would be capable of measuring the time-of-flight of the respective signals, ultrasound is in particular suitable for the present application, since the time-of-flight (where the typical distance is between 0.2 and 2 meter) can be measured in milliseconds rather than in nanoseconds, which allows for easy and accurate measurement with low cost processing equipment. The system of the invention can be produced at very low cost, since piezoelectric acoustic transceivers are very cheap.

The system of the invention is easy to control, with a simple user interface which does not require additional equipment such as a remote control. Other qualities of the system of the invention are its robustness, its independency from environmental conditions, its one-dimensional recognition of control movements, and its low processing power requirements. The further advantage of an ultrasound sensor is that it is less influenced by changing ambient light, temperature and humidity conditions.

Said ultrasonic transmitter and receiver, processing means, and/or light control means, preferably extend in the lamp housing, and said ultrasonic transmitter and receiver preferably are a combined ultrasonic transceiver. Thereby a compact and easy to install lighting system is provided.

It is desirable that the ultrasound controlled lighting system is easy to produce in mass quantities, with low cost components, and has small dimensions so that it can be built- in in even in a system comprising small lamps.

In a preferred embodiment the lighting system in accordance with the invention comprises a LED driver and a pulse width modulator arranged to adjust said light beam properties; a DA-converter, an ultrasound driver and an ultrasonic transmitter arranged to convert a digital transmit signal into the transmission of an ultrasonic pulse; an ultrasonic receiver and an amplifier arranged to receive reflected ultrasonic signals and transform said ultrasonic signal in a voltage, and a comparator arranged to generate a digital receive signal if said voltage is greater than a predetermined threshold; a processing means arranged to derive a time-of-flight signal representing the time differences between said digital transmit and receive signals and to send control signals to said light control means in dependence of said time-of-flight signal. Preferably said processing means, said pulse width modulator, said DA-converter and said comparator are integrated in a single microcontroller chip. Said microcontroller chip is preferably chosen from the single-chip 8-bit 8051/80C51 microcontroller family, preferably comprising small sized RAM and ROM, preferably smaller than 4kB ROM and smaller than 512 B RAM.

Preferably said ultrasonic transmitter and said ultrasonic receiver are integrated in a piezoelectric ultrasound transceiver.

Preferably said transmitting ultrasound driver and said receiving ultrasound amplifier are integrated in a pre-processing circuit. Said pre-processing circuit preferably further comprises a second order filter for filtering out low frequent signals from said received signal.

Brief description of the drawings

The lamp 1 as shown in figure 2 comprises a plurality of LEDs and an ultrasonic transceiver built-in in the centre of said plurality of LEDs. Also a processing means for translating the signals of the transceiver into control signals, and control means to adjust the light properties are built-in.

If the ultrasonic transceiver is switched on it will send an acoustic signal. If an object is present the acoustic signal will be reflected at the object and will be received by the ultrasonic transceiver inside the lamp. The time difference, called the time-of-flight, between sending and receiving the acoustic signal will be measured. If the distance between the object and the lamp 1 is changed another time-of-flight value will be measured. The detected movement of the object is a one-dimensional movement (the object must stay in the ultrasound beam cone). The change in time-of-flight will be translated into a change in a digital control signal. This control signal will control the properties of the light beam, like colour, intensity or colour temperature, etc. The object may be the hand 2 of a user. Thus a one-dimensional movement of the hand 2, like up/down or left/right direction (depending on lamp position, horizontal or vertical) can control the light beam properties.

In commercially available pulse echo distance measurement units of the transmitter - reflector - receiver type (TRR), the most common task is to measure the distance to the closest reflecting object. The measured time is the representative of travelling twice the distance. The returned signal follows essentially the same path back to a receiver located close to the transmitter. Transmitting and receiving transceivers are located in the same device. The receiver amplifier sends these reflected signals (echoes) to the micro-controller which times them to determine how far away the object is, by using the speed of sound in air.

The time-of-flight of acoustic signals is commonly used as a distance measurement method. A time-of-flight measurement, as illustrated in figure 1 is formed by subtracting the time-of-transmission (T in figure 1) of a signal from the measured time-of-receipt (R in figure 1). This time distance information will be transferred into a binary code in the microprocessor to control the lamp properties.

In figure 2 a hand 2 is the obstacle/object and a table 3, floor or ceiling is the reference. The ultrasonic transceiver sends an ultrasonic wave in the form of a beam cone 4. If the distance y from the transceiver to the reference is 1.5 m, the total travel distance for the ultra-sound beam 4 is 2*y = 3 m. The time-of-flight then is 8.7 ms (at an ambient temperature of 25 ⁰ C). If the distance x from the transceiver to the hand is 0.5 m, the time-of-flight is 2.9 ms. If the required accuracy of control steps of the hand movement is 2 cm (time-of-flight steps of 0.12 ms), and the range of control is for instance 64 cm, there are 32 control steps, which allows for 5-bit control.

The control signal as shown in figure 3 is made by the movement of the hand 2 in a one-dimensional vertical direction in the ultrasonic beam 4. At Tl=Is the hand 2 is outside the beam, the reference value is measured, and lamp control is disabled (stage A). At T2=2s the hand 2 moves into the beam 4 and is held there for more than 1 second until at T3=3s lamp control is enabled by the microcontroller (stage B). Then the hand 2 moves up between T3=3s and T5=5s, whereby for instance the intensity of the lamp 1 is increased by the microprocessor (stage C). At T6=6s the hand is withdrawn from the beam 4 so that the reference value is measured, and lamp control is disabled thereby (stage D). An accidental movement of the hand 2 in the ultrasonic beam 4 as shown at T7=7s does therefore not result in an accidental adjustment of the lamp properties (stage E). Hence, the lamp control is activated by holding an object in the ultrasonic beam 4 for more than 1 second.

The ultrasonic beam cone angle is important to provide reliable hand control. In Figure 4 the beam radius at the reference position is r. The beam radius rh at the hand position must be high enough to have optimum control by hand. During control of a lamp property the average beam radius should be equal to approximately half the length of the average hand shape as shown in figure 5. If the total control range is around X/2 (for a lamp/table application), the ultrasound beam angle at the minimum beam radius during control of the lamp property will be around Lh/2. For example: if Lh = 150 mm and X = 1.5 m, the ultrasound beam angle θ should be 11°. The relationship between the vertical distance X and the beam angle as function of the beam radius is shown in figure 6. Lamp control will be possible if the hand 2 is in the narrow ultrasound cone 4 as shown in figure 7. Reduction of a wide ultrasound beam 4 and an increase of sound pressure level (SPL) of an ultrasonic transceiver 5 may be achieved by a horn 6 as shown in figure 8.

In order to reduce the costs of the lamp to a minimum and to have the possibility to control all possible lighting parameters like colour, intensity, etcetera, the electronic circuit needed for carrying out the control functions is integrated in the lamp. The microprocessor used for gesture control is also integrated in the LED control microprocessor to reduce the cost even more. The integration of the ultrasound sensor in the lamp makes low cost, high volume production possible.

With reference to figure 9, as explained above the micro-controller sends a pulse to the ultrasound transmitter of the ultrasound transceiver 5. A digital pulse signal is generated by the control part 13A of a micro-controller 13, and converted by DA- converter 17 in said micro-controller 13 into an electric pulse. This pulse will be amplified by the amplifier 18 in the pre-processor 10 (shown in more detail in figure 10) to a value that can be used by the ultrasound transmitter part of the ultrasound transceiver 5. Then the piezo-electric ultrasound transceiver 5 sends an acoustic signal (for instance at a frequency of 4OkHz). An object will reflect this acoustic signal. The pre-processor 10 will receive the reflected signal via the ultrasound transceiver 5. In order to reduce the influence of outside disturbances the signal is filtered by a 2nd order High-Pass filter 11 of for instance 2OkHz (= fc). After filtering the signal is amplified by amplifier 12 in the pre-processor 10.

Microcontroller 13 comprises a comparator 14, which creates a digital pulse signal from the electric signal received from the pre-processor 10, which can be processed by the micro-controller 13.

The micro-controller 13 further comprises a LED driver part 13B, with a modulator 20, which is connected to the LED driver 19, and part of the ROM 15 and the RAM 16, which is shared, with the control part 13A of the micro-controller.

Such a micro-controller 13, arranged to drive a LED, is well known in the art, but is further programmed to perform the control functions as described above. The microcontroller can be a simple processor, for instance of the 8051 -family. The size of the ROM 15 can be as low as 2kB and the size of the RAM 16 can be as low as 256 bytes.

Figure 11 shows a lamp comprising a housing with a standard incandescent lamp type fitting, ten LEDs 21 arranged in a circle, a transceiver 5 in a horn 6. All the electronic components like the micro-controller 13, pre-processor 10 and LED driver 19 are built-in in the housing 23. Thereby a very compact lighting system is obtained, which requires no further external accessories to be operated and controlled.

Now with reference to figures 12-18 an extended lighting system is described that allows control of light parameters by gesture (e.g. hand displacement) in a XY-plane, which extends perpendicular to the Z-axis, being the axis of the light beam of the lamp. This will introduce additional possibilities for gesture light control, which can be combined with the above described method for gesture light control in the Z- direction based on time-of-flight measurements. For example it is possible to pull or push the light beam by hand movement in a certain direction. Also light control is possible for example by hand movement in a circular motion. By using also the time- of-flight determination as described above, a combination of two light controls is possible, like light beam deviation and light intensity could be controlled at the same time. Alternatively the gestures in the XY-plane can be used for switching from controlling one light beam property to another light beam property.

A first embodiment is described with reference to figures 12-14. According to figure 12 the lamp 1 is provided with three piezoelectric ultrasound transceivers 5 mounted in a triangular shape, which are arranged such that the axes of their ultrasound beams extend parallel to the axis of the light beam 4 and in said light beam 4. The position of an object, such as the hand 2 in the XY-plane, is determined by object detection by said three transceivers 5. Said position is determined by sequentially transmitting an acoustic pulse from one transceiver 5 at a time. Each of the three transceivers 5 determines if a reflected signal is received after each pulse is sent by one of said transceivers 5.

The object position determined by this sequential transmitting and parallel receiving method is translated into a binary code. From this code the XY-position of the object is determined, and is translated into light control instructions, like light beam deviation or other light controls like colour, intensity, focus, etcetera.

In figure 13 a time diagram is given of the proposed method. The three transceivers subsequently send acoustic signals on three time intervals tθ, tl and t2. The three transceivers will determine if an echo signal sent by a transmitter is received, which depends on the position of the hand 2. In figure 13 a dotted block indicates that the received echo signal strength is below a predetermined threshold and the echo signal is given value 0. If the echo signal strength is equal to or above said threshold the echo signal is given the value 1. This echo information is represented in table 1.

Table 1 : example of information of sequential transmitting and parallel receiving method

This binary information is translated into a position in the XY-plane by following equations:

Where n is the total number of transceivers Wx and Wy are weight factors k and m are transceiver indices

The X and Y value determine the actual position of the hand 2 in the XY-plane. If the hand 2 is moving to a certain direction the X, Y values change. From these values the hand displacement direction is known.

If the hand 2 moves outside the control range in the X or Y direction or both, the values are fixed to a constant value. The movement direction and distance of the hand 2 and/or its actual position will be translated into a light control instruction, e.g. a deflection action of the light beam in a certain XY direction.

A hand generally has a spherical shape, which causes beam scattering effects. To reduce the influence of scattering on the measurement result horns of e.g. 10 degrees beam angle are preferably placed on the transceivers. An extra advantage for using a 10 degrees horn is a higher sound pressure level of the sent signals.

The above method provides at least four/five valid steps in each direction. The calculated XY-positions are translated into a light control value in the user interface. As an example a sequence of hand movements comprising 8 steps is shown in figures 14A-14H, and for each step a table with transmitted and received binary values for each transceiver is shown below, with the calculated values for X and Y.

Time Sequential Transmitting Parallel Receiving

Tl T2 T3 Rl R2 R3 t = to Tl ₀ =I T2 ₀ =0 T3o=O Rl ₀ =I R2o=l R3 ₀ =l t = ti Tl ₁ =O TCi=I T3i=0 RIi=I R2i=l R3i=l t = t ₂ Tl ₂ =O T2 ₂ =0 T3 ₂ =l Rl ₂ =I R2 ₂ =l R3 ₂ = l

Table 2a (figure 14 A, step 1): X = O, Y = -0. 5

Time Sequential Transmitting Parallel Receiving

Tl T2 T3 Rl R2 R3 t = to Tl ₀ =I T2o=O T3 ₀ =0 Rl ₀ =I R2 ₀ =0 R3o= l t = ti Tl ₁ =O TCi=I T3i=0 Rl ₁ =O R2,= 0 R3i=0 t = t ₂ Tl ₂ =O T2 ₂ =0 T3 ₂ =l Rl ₂ =I R2 ₂ =0 R3 ₂ =0

Table 2b (figure 14B, step 2): X = -0.5, Y = -0.5

Time Sequential Transmitting Parallel Receiving

Tl T2 T3 Rl R2 R3 t = to Tl ₀ =I T2 ₀ =0 T3o=O Rl ₀ =I R2 ₀ =0 R3 ₀ =0 t = t, Tl ₁ =O TCi=I T3,= 0 RIi=O R2i=0 R3i=0 t = t ₂ Tl ₂ =O T2 ₂ =0 T3 ₂ =l Rl ₂ =O R2 ₂ =0 R3 ₂ =0

Table 2c (figure 14C, step 3): X = -1, Y = -0 .5

Time Sequential Transmitting Parallel Receiving

Tl T2 T3 Rl R2 R3 t = to Tl ₀ =I T2o=O T3 ₀ =0 Rl ₀ =O R2o=O R3 ₀ =0 t = ti Tl,= 0 TCi= I T3,= 0 Rl ₁ =O R2i=0 R3i=0 t = t ₂ Tl ₂ =O T2 ₂ =0 T3 ₂ = l Rl ₂ =O R2 ₂ =0 R3 ₂ =0

Table 2d (figure 14D, step 4): object outside range X, Y not changed

Time Sequential Transmitting Parallel Receiving

Table 2e (figure 14E, step 5): X = 0, Y = -0.5

Table 2f (figure 14F, step 6): X = +0.5, Y = -0.5

Table 2g (figure 14G, step 7): X = +1, Y = -0.5

Table 2h (figure 14H, step 8): object outside range X, Y not changed

Now with reference to figures 15-18 an second embodiment for determining the hand position in the XY -plane will be described. The method is comparable with the above described method, but distinguishes itself in that only one ultrasound transceiver 5 is used, which is rotated in the lamp around the lamp axis, such that object localization can be achieved in one revolution. According to figures 15 and 16 the lamp 1 comprises an array of LEDs 21 and a piezoelectric ultrasound transceiver 5 mounted on a rotating cogwheel 30, such that the transceiver 5 moves along the circumference of the lamp 1. The cogwheel 30 is driven by another small cogwheel 31, which is connected to a stepper motor 32. The transceiver rotation speed is higher than the hand movement in the XY-plane. For example if the transceiver rotation speed is 4Hz, then the time needed for one revolution of the transceiver is 250 ms. Within this period the xy-position of the object is detected, in which period the hand 2 will not have been moved significantly.

In order to determine the transceiver position along the circumference of the lamp, a reference transceiver position is defined by a blocking filter 33 for ultrasound signals arranged at said position. The reference calibration to determine said reference position can be carried out in one transceiver revolution. The rotation of the transceiver 5 will be activated when an object, such as hand 2 is placed in the transceiver detection range.

Said position is determined by transmitting an acoustic pulse from said transceiver 5 and determining if a reflected signal is received, and then rotate said transceiver 5 to the next position and repeat this step, until such determination is achieved at twelve positions, as shown in figure 17.

In figure 18 a time diagram is given of the proposed method. The transceiver subsequently sends acoustic signals (TO ... Tl 1) on twelve time intervals tθ, tl ... ti l. At each step the transceiver 5 will determine if an echo signal is received (RO ... RI l), which depends on the position of the hand 2. In figure 18 a dotted block indicates that the received echo signal strength is below a predetermined threshold and the echo signal is given value 0. If the echo signal strength is equal to or above said threshold the echo signal is given the value 1. An example of this echo information is shown in table 3.

Table 3

This binary information is translated into a position in the XY-plane by the following equations:

n-l p=0

Where n is the total number of measurements during one sensor revolution Wx and Wy are weight factors

The weight factor values depends on the transceiver position during the measurement compared to the reference position.

Now with reference to figures 19-20 a third embodiment for determining the hand position in the XY-plane will be described. According to figure 19 and 20 the lamp 1 is provided with two piezoelectric ultrasound transceivers 5, which are arranged such that the axes of their ultrasound beams extend parallel to the axis of the light beam 4 and in said light beam 4. Alternatively, in order to achieve more accurate results, more transceivers can be applied, for instance three transceivers, which are positioned in a triangle as in figure 12. The position of an object, such as the hand 2 in the XY-plane, is determined by determining the time-of-flight by said transceivers 5. Said position is determined by sequentially transmitting an acoustic pulse from one transceiver 5 at a time. After each pulse is sent by one of said transceivers 5, each of the transceivers 5 determines the time-of-flight of the reflected signal in accordance with the earlier described method. In principle the method needs only one transmitter to send an acoustic pulse and two receivers to determine the time-of-flight of the reflected signal.

The position of the object is determined by combining the time-of-flight measurements of said two or more receivers. In order to achieve reliable determinations the distance between the ultrasound sensors must be sufficiently high.

If for instance the accuracy of a time-of-flight measurement is 2 cm, for reliable position determination of an object at 1 m from the transceivers the distance between two sensors must be at least 28 cm. The ultrasound beam angle in this case must be sufficiently high.

Example 1 : The number of sensors is two, one transceiver (transmitter & receiver) and one receiver.

The distance in a XY-plane can be calculated as follows:

va, _r

v _fl , _r - (TOF _{n R2} ) _{ι ι0} = ^{x, -xj + (y, -y _o f + V(x ₀ -X ₂ ) ² + {y ₀ - yj = b

where v _air = speed of sound at room temperature, is 344 m/s. To simplify the calculations the sensors are placed in the XY-plane. The receivers are placed so that both are on the X-axis and one on the Y-axis. The only parameter that has to be defined for the sensor units is the distance d, between the sensors. With these assumptions the new coordinates for the transmitter and the receivers become:

Receivers: R,= (0,0)

R ₂ = (d,0) Transmitter: (0,0)

With the new coordinates above-mentioned expression become much easier to handle:

for t=to:

W(*oJ ² +(yoJ ² W(*o - ^« 0 ² +G'oJ ²

The object position x _o ,y _o at t=to will be

This position at t=t ₀ is used as the initial position of the hand. The same measurements will be repeated at another time t=ti for detecting movement distance direction of the object.

The movement direction is calculated as follows:

If Δx is positive then the hand moves in the left direction, if Δy is positive then the hand moves in the downwards direction. Thus in this case the hand moves towards the southwest direction. This position change is translated into a binary code and used for controlling the light beam properties, for instance for deviating the light beam into the same direction as object moves, towards the southwest direction.

Example 2: In order to be able to determine the displacement of the object in the z- direction an additional transceiver is included. Determination of the displacement in the z-direction can be used for additional menu control. In this example one transmitter and three receivers are used, in a configuration as in figure 12. The basic principle is the same as in example 1. Time-of-flight measurements are performed on three sensors now instead of two: one transceiver and two receivers.

Distance calculation can be performed from the transmitter to the object (hand) and from the object to the three receivers by the following equations:

v _aιr ^■ (TOF _n J _n L ₀ = VU -*o) ² +U -^o) ² + U -Zo) ² + V(*o -*i) ² +GO -*) ² +(Z ₀ -*!) ^{2 v} a,r ^■ (τoF _nja L ₀ = VU - X ₀ Y + (y, -y _o f + U - Z ₀ ) ² + VU - * ₂ ) ² + iy ₀ - y ₂ Y + U _> - ^Z 2 Y

V _aιr ^■ (TOF _{n R3} L ₀ = VU -xj +fa -yj +(Z ₁ -Z ₀ ) ² + VU -X ₃ ) ² +U -^ ₃ ) ² +(Z ₀ -Z ₃ Y

These are 3 equations with 3 unknowns. The calculation result is: (xo)t= _t o, This is the initial position of the object.

These measurements and calculations are repeated at t=ti for detecting movement distance and direction of the object, which will result in (x _o ) _t =u, (yo)t=ti, (z _o )t=ti, etcetera. Movement direction is calculated as follows:

A^ = (Z ₀ L _o -( ^z o L,

If Δx is positive then the object moves in the left direction, if Δy is positive then the object moves in pull direction and if Δz is positive then the object moves in a downwards direction.

Thus the object moves towards the southwest - downwards direction (in the XYZ- space). This position will be translated into a binary code and used for light beam properties control, for instance in this case for deviating the light beam into the same direction as the object, towards the southwest direction. Another example of the use of this position information: the movement in the XY-directions controls the direction of the light beam deviation and movement in the Z-direction controls the magnitude of the light beam deviation.

Example 3:

In this example a system with three transceivers is described, in a configuration as in figure 12. This provides the possibility to measure the object position three times from different transmitter positions.

First at t=t ₀ transmitter Tl will send an acoustic signal to the object. The signal will be reflected at the object and will be received by the three receivers (Rl, R2, R3).

v _βI , ^■ (TOF _TURl L ₀ = V(*. -J ₀ ) ² +(K -.Vo) ² +( ^Z i - ^Z o) ² + V(*o -*,)' + GΌ -JV ₁ ) ² + ( ^Z ₀ ^{" Z} ₁ ) ²

v _aιr ^■ (TOF _{n J12} ) = >/(*i -*o) ² +(?! ^~ y ₀ Y +( ^z ι - ^z oY + V(*o -* ₂ ) ² +GΌ ->0 ² +( ^Z ₀ - ^Z ₂ ) ²

These are 3 equations with 3 unknowns. The calculation result

At t=ti transmitter T2 will send an acoustic signal to the object. The signal will be reflected at the object and will be received by the three receivers.

To have a more reliable position of the object an average of the three measurements at t=t ₀ , t=t ₁ and t=t ₂ is calculated. This is possible because the sample frequency for object localization is much higher than the object movement speed.

This position is the initial position of the object.

These measurements and calculations will be repeated at tb (t ₃ , t ₄ , ts) for detecting movement and movement direction of the object, which will result in (x _o ) _t b, (y _O )tt _> ,

(Zθ)tb-

Movement direction will be calculated as follows:

If Δx is positive then the object moves in the left direction, if Δy is positive then the object moves in pull direction and if Δz is positive the object moves in a downwards direction.

Thus the object moves towards southwest - downwards direction (in the XYZ-space). This position will be translated into a binary code and used for light control purposes, for instance it will deviate the light beam into the same direction as the object moves, in this case towards southwest direction, and at the same time for instance the light intensity will be decreased. Another example of the use of this position information: the movement in the XY-directions controls the direction of the light beam deviation and movement in the Z-direction controls the magnitude of the light beam deviation.

With reference to figures 21-25 a lamp 1 is described which is capable of continuous focus control (figure 21 A) and deflection (figure 21B and 21 C) of a light beam in a wide range as well as in a small region, without moving any physical parts of the lamp 1. This lamp is preferably combined with the XY-plane gesture control system as described above for changing the direction or focus of the light beam.

According to figure 22 the lamp 1 is divided into three separated ring shaped parts 4OA, 4OB, 4OC, each comprising an array of LEDs 21. Said LEDs may be multicoloured, so that the lamp can show many colours of choice. Although the figures show a circle shape of the arrays, other shapes like a rectangular shape are also possible. The central part 4OA of the lamp comprises a plastic lens 41 in front of the LEDs 21 for focussing the central light beam. An intermediate part 4OB comprises a ring of LEDs without a lens. The LEDs in the central and intermediate parts 40A/B are arranged such that their axes of their light beams are parallel with the lamp axis. In the third part 4OC the LEDs 21 are mounted at a angle with the lamp axis, which angle is between 0 and 90 degrees, for instance 40 degrees. The LEDs are mounted such, that at a predefined minimum use distance from the lamp (for instance 1 m) away, the light beams of each LED overlaps with its neighbour's, such that a continuously lighted area is obtained.

The LEDs are mounted in a metal housing having walls separating the three groups of LEDs, and which performs a heatsink function for cooling purposes.

With reference to figure 23 a gesture light control system as described above (or alternatively an ordinary Remote Control) sends light beam position or focus instructions to a micro-controller. The micro-controller translates this information into instructions as to which LEDs 21 have to be selected and as to the intensity of each of the LEDs 21. An expander/selector 42 is used for selecting the large amount of drivers 43 and the LEDs 21 connected thereto. For a point light source the relationship between the perceived brightness B and the measured illuminance E is:

which is a non-linear behaviour that has to be compensated. If the average perceived brightness is to be kept constant during control of the light beam than the average illumination E has to be constant. Therefore the total luminous flux incident on a surface per unit area is kept constant during control of the light beam.

Figures 24A-24G schematically shows how the direction of the combined light beam in the lamp of figure 22 is smoothly changed from a downward direction in figure 24A to a laterally slanting direction in figure 24G (lighter hatched areas represent lighter areas/LEDs, more densely hatched areas represent darker areas/LEDs). For carrying out this control instruction the micro-controller in the lamp is arranged to gradually change the brightness of individual LEDs such that the impression of said smooth change in direction of the combined light beam is obtained.

Figures 25A-25E schematically shows how the angle of the combined light beam in the lamp of figure 22 is smoothly changed from a broad beam having a large angle in figure 25A to a focussed beam having a small angle in figure 24E. For carrying out this control instruction the micro-controller in the lamp is arranged to gradually change the brightness of individual LEDs such that the impression of said smooth change in angle of the combined light beam is obtained.

Figure 26 schematically shows how a light beam is transferred along an array of separate lamps 1 as described with reference to figures 21-25. Said lamps 1 are provided with radiofrequency communication means 55 (as shown in figure 31), such as ZigBee or Z- Wave standard communication means, so that the micro-controllers of each of the lamps 1 can communicate with each other. Alternatively, a wireless ultrasound communication method as described below can be used, making use of the already present ultrasound transceivers 5. The lamps are suspended from a ceiling 50, and the light beam 4 follows a person 51 walking on the floor 53. Referring to figures 9 and 10, the micro-controllers 13 of the lamps are either preprogrammed for a particular lamp configuration, wherein the location, i.e. the order of lamps and the distance between them, are known, or the micro-controllers 13 are programmed to perform a calibration procedure, in order to determine the location of the lamps by user input and to be assigned a unique identifier, and to set the responsive area of each lamp's ultrasound transceiver so that they are narrowly adjacent but do not overlap. The latter can for instance be achieved by adapting the sound pressure level of the transceiver 5, by adapting the receiving gain of the preprocessor 10, and/or by changing the threshold level of comparator 14, until just no reflected signal from neighbouring transceivers 5 is received.

The micro-controller 13 in the first lamp 1 where an object is detected will assume a master role in the wirelessly interconnected network of lamps 1 , and will direct the light beam to said object. Furthermore it will determine the direction and speed of movement of the object. The light beam of said lamp 1 will move in the same direction and at the same speed as the object, and simultaneously the adjacent lamp 1 where the object is moving to will receive information about the arrival of said object (location, direction and speed), so that as soon as the object arrives at the border area between said two lamps 1, LEDs 5 of said adjacent lamp 1 will built-up a beam shining at said moving object's location while the beam of the LEDs of the first lamp 1 shining on said location will be dimmed to zero. In that manner a smooth, moving transition of beams between the two lamps 1 is achieved. This process continues as long as the object is moving in the area covered by the transceivers 5 of the group of lamps 1.

Figures 27 A-F schematically show an application of the invention, where a light beam is smoothly moved between the lamps in order to cast the beam 4 on different products by the movement of a hand 2 over said products 52. In this manner a customer can for instance indicate which product 52 he wants to buy.

Wireless communication between different lamps 1 in the system can also be achieved by using the ultrasound transceivers 5 as data transmitters and receivers, as shown in figure 28 between transceivers Sl and S2. Transceivers 5 of adjacent lamps 1 receive the reflected signals of each other, and by coding data information into said ultrasound signals the micro-processors 13 of said lamps 1 can communicate with each other with any suitable communication protocol known in the art. A simple example thereof is shown in figure 28. If data communication in this manner is combined with the light beam movement method as described above, the micro- controllers are programmed such, that two different sensitivity levels are simultaneously present. At one level the responsive areas of the transceivers 5 are narrowly adjacent but do not overlap as described above, and at the second level the responsive areas of the transceivers 5 overlap such that communication between the micro-controllers 13 is possible. Also the narrower responsive areas, or if more appropriate the wider responsive areas, can be used for gesture control of the lamp properties as described before.

By using the ultrasound wireless communication between the lamps 1 a user can control certain lamp properties of all the lamps 1 in the system at once, if the micro- controllers 13 are ordered to copy these lamp property values to the neighbouring lamps 1. For instance it is possible to define a certain "copy to all lamps" gesture that is to be made by the user's hand so that the change in lamp properties caused by control gestures thereafter are copied to all other lamps 1 in the system.

In order to communicate a message for all other lamps in the network, and avoid interference of returned messages of different lamps, one micro-controller 13, for instance in the lamp 1 that receives the hand gesture reflections, may be made master. The master will require a different delay in reaction time for each other lamp 1 in the network, which are slaves, and which are each identified by a unique identifier. Said identifiers may be used to generate said different delay times for each lamp.

Two different possibilities for coding data into the ultrasound signals are shown in figures 29 and 30.

According figure 29 a time based data transfer method is used, wherein the ultrasound transmitter of Sl of figure 28 sends a pulse train of a fixed frequency (for instance 40 kHz), which is equal to the resonance frequency of the piezoelectric transceiver 13. As long as the vertical distance remains constant the time-of-flight has a constant value, and is stored as the transmitting time period T. If the receiver of S2 detects a signal T after it was sent by Sl, then a logical "1" is received. If no signal is detected after T, a logical "0"is received.

According to figure 30 a frequency based data transfer method is used. The frequency of the pulse train sent by S 1 is slightly different from the aforementioned resonance frequency (for instance 41 kHz for a logical "l"and 39 kHz for a logical "0"). The receiver detects the difference in frequency of the received pulses, preferably by using the zero-crossing measurement method known in the art, and thereby detects if a "0" or a "l" is sent.

The lamps 1 can also be provided with ultrasound transceivers that are directed directly to the other lamps in the network, in order to make use of this communication protocol without the need to use reflected signals, so that lamps can communicate with each other over larger distances. For instance, each lamp can be provided with 4 designated communication transceivers, each directed outwardly at mutual angles of 90 degrees, and each covering a 90 degrees area detection angle, such that a 360 degrees area around the lamp is covered for communication purposes with other lamps.

The communication means as described above can also be used to wirelessly distribute new software, such as new gesture control software with extended functionality or new lamp driver software, to the lamps, as illustrated in figures 31 and 32. Referring to figure 31, lamps are shown schematically as in figure 9, wherein new software is copied from flash ROM 15 bank N of a first lamp 1 on the left side to a second lamp 1 on the right side, so that both lamps will have the same software. This method can be used to provide all the lamps in the system with the same software. Each lamp 1 is provided with wireless communication means, such as an RF or infrared module 55, but preferably the ultrasound transceiver 5 is used with the above described ultrasound communication method.

In this manner it is for instance possible to automatically copy the latest software from a new lamp that is added to a lamp system to lamps that have already been in use for a period of time, and which has outdated software. It is also possible for a user to develop his own user defined software, and distribute said software easily in the lamp system. Further, this method can be used in the factory where the lamps are made.

An example of a communication protocol is schematically shown in figure 33. If a new lamp 1 is added to the system, the software will first check if the lamps 1 are able to communicate with each other, and if the hardware is suited for the new software (by checking the hardware code). The new lamp 1 will act as master and send its own software to the other lamp or lamps 1 in the system, which act as slave.

The software will first be copied from bank N of the ROM into the RAM 16 in the new lamp. Then it will be transferred using the wireless method to the RAM 16 of the old lamp or lamps 1. If the transfer has been confirmed succesful, the software will be copied into a bank of the ROM 15 of the old lamp or lamps 1.

Referring to figure 32 new software is sent from a personal computer 56 or a mobile telephone, which may be connected to the internet, to a lamp 1 by means of a wireless data transfer module 57, which is connected to the personal computer 56 or the mobile telephone through a USB connector. The wireless data module 57 is provided with wireless communication means, such as RF or infrared, but preferably the wireless data module 57 is provided with at least one ultrasound transceiver 5, and uses the above described wireless communication method using ultrasound.

Figures 34-36 show how a lamp system is being configured to communicate with each other, by using gesture control. A multitude of lamps 1 may be suspended from a ceiling in a line array, or in any other configuration. In figures 35, 36 three tables 3 are shown. A user wishes the lamps 1 suspended above the two tables 3 on the right side to behave the same, for instance in terms of on/off switching and brightness control, whereas the lamp 1 suspended above the table 3 on the left side is designated to behave differently. To that end, the lamps 1 above the two tables 3 on the right side are being configured by using gesture control (for instance by a movement of hand 2 in the ultrasound beam 4 as shown in figure 34) to communicate control messages between each other with any appropriate wired or wireless communication method, for instance a wireless RF method (such as ZigBee or Z-Wave) or a light or ultrasound communication method, as described above. As shown in figure 34, starting from a neutral situation A at time Tl wherein the ultrasound beam of a lamp is reflected on a table 3, on time T2 the user moves his hand 2 into the ultrasound beam 4 such that the detected time-of-flight is substantially shorter, as shown in situation B. Thereby, after a predetermined time, control of the lamp is enabled, and at T3 the user moves his hand 2 upwardly (in the Z-direction) in ultrasound beam 4 and at T4 the hand 2 is moved out of the beam 4. The microprocessor 13 can also be programmed to detect other gestures, such as the gestures in the XY-plane perpendicular to the ultrasound beam (as described before with reference to figures 12-20). By said detection the lamp 1 is set in a connection mode as shown in situation C, and will start to search for other lamps 1 that are also in connection mode for a predetermined period of time (for instance 5 minutes), as shown in situation D. The lamp 1 will transmit a light signal in order to indicate to the user that it is in connection mode.

The user can then repeat this process with the other lamps he wishes to connect to each other, as shown in figure 35, such that all the lamps that are in connection mode at the same time will establish a network connection with each other and the end result as shown in figure 36 is achieved, wherein the three lamps 1 on the right hand side are connected with each other and communicate the lamp gesture control signals that are received by any of said three lamps 1 between each other so that they behave identically. In the configuration process a network will be created using a network and communication protocol, as known in the art, wherein each lamp will receive and store a unique device identifier code in memory. The lamps may for instance be configured such that upon the first detection of a predetermined gesture signal at one lamp in a network, said lamp will be made master, and the other lamps will be made slaves through said communication protocol (as described above) in order to communicate the control signals in said network. Different independent communication networks can be created within a lamp system in this manner. After said predetermined period of time the lamp control mode is disabled and the lamp will return in the neutral situation as shown in situation E. Although the invention is described herein by way of preferred embodiments as example, the man skilled in the art will appreciate that many modifications and variations are possible within the scope of the invention.