WO2010070520A1

WO2010070520A1 - Lighting system for guiding a person

Info

Publication number: WO2010070520A1
Application number: PCT/IB2009/055536
Authority: WO
Inventors: Willem L. Ijzerman; Anthonie H. Bergman
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2008-12-15
Filing date: 2009-12-07
Publication date: 2010-06-24
Also published as: TW201029517A

Abstract

A control device for an illumination light source, comprising a light sensor for detecting a visible light illumination characteristic, and control circuitry adapted to select at least one of a number of predetermined visible light illumination characteristics based on a signal received from the light sensor and to output a control signal corresponding to the at least one selected illumination characteristic for controlling the illumination light source, wherein the at least one selected visible illumination characteristic is different than the illumination characteristic detected by the light sensor. By means of the invention it is possible to decrease the energy consumption of an illumination light source as well as provide an improvement in illumination quality and comfort.

Description

LIGHTING SYSTEM FOR GUIDING A PERSON

TECHNICAL FIELD

The present invention relates to a control device for an illumination light source and a lighting system comprising such a control device. The present invention also relates to a corresponding method.

BACKGROUND OF THE INVENTION

Recently, much progress has been made in increasing the brightness of light emitting diodes (LEDs). As a result, LEDs have become sufficiently bright and inexpensive, to serve as a light source in for example illumination arrangements such as lamps with adjustable color. By mixing differently colored LEDs any number of colors can be generated, e.g. white. An adjustable color lighting system is typically constructed by using a number of primary colors, and in one example, the three primaries red, green and blue are used. The color of the generated light is determined by the LEDs that are used, as well as by the mixing ratios. To generate "white", all three LEDs have to be turned on. By using LEDs it is possible to decrease the energy consumption, a requirement, which is well in line with the current environmental trend. For further decreasing the energy consumption of the illumination arrangement it is possible to include light sensors and presence detectors, which will detect changes in ambient lighting and approaching persons, respectively. Such additions may in turn lead to a decrease in the time the illumination arrangement is active, as well as an intensity decrease by taking into account the ambient lighting.

In a lighting system comprising a plurality of the above described illumination arrangements, it may be useful to include a hardware component with the illumination arrangement for allowing some sort of communication between the different illumination arrangements, thereby further decreasing the energy consumption. For such communication, a number of wireless technologies have been developed, including for example RF transmission circuitry supporting IEEE 802.11. However, a problem with such wireless technologies are that the lead to a great increase of the cost of the illumination arrangement and thus the resulting lighting system. Hence, there is a need for an improvement in relation to the communication between lighting arrangements in a lighting system, and more specifically that overcome or at least alleviates the prior art problems with expensive additional hardware components.

SUMMARY OF THE INVENTION

According to an aspect of the invention, the above is met by a control device for an illumination light source, comprising a light sensor for detecting a visible light illumination characteristic, and control circuitry adapted to select at least one of a number of predetermined visible light illumination characteristics based on a signal received from the light sensor and to output a control signal corresponding to the at least one selected illumination characteristic for controlling the illumination light source.

The general concept of the present invention is based on the fact that it is possible to use the actual visible illumination of an indoor and/or outdoor environment for also distributing a current illumination characteristic of an illumination light source. That is, the inventive control device will allow detection of a current illumination characteristic state in the surrounding, and control a thereto connected illumination light source such that it as a result emits a predetermined illumination characteristic that differs from the detected state. Accordingly, it is for example possible for two different control devices connected to two different light sources to be aware of one another, without having to resort to complicated RF communication techniques. The inventive control device need only detect the light illumination characteristic in its surrounding, and respond by emission of light according to at least one of a number of predetermined visible light illumination characteristics. For example, the at least one selected visible illumination characteristic may be different than the illumination characteristic detected by the light sensor. An advantage with the invention is thereby decreased energy consumption as well as an improvement of the illumination quality and perceived comfort. As mentioned, there is furthermore no need for the inclusion of hardware modules for providing RF communication, as no data is communicated, but rather just a state of illumination light source. More specifically, no additional communication channel is needed through which different information is sent, but instead the illumination characteristic of light emitted by the illumination light source will be sufficient.

In an embodiment, wherein the control signal is encoded by the control circuitry such that the selected at least one visible illumination characteristic is modulated to comprise a frequency component. By such an implementation, it is possible to for control the illumination light source by using pulse width modulation (PWM). PWM may be used for controlling the brightness/intensity of the illumination light source, but may according to the invention also be used for modulating the emitted light which in turn may be detected by the light sensor. In a preferred embodiment, the control device further comprises sensor for detecting the presence of a moving object, such as an approaching person or an approaching vehicle, in a surrounding of the control device. This detection can be done via IR, ultrasound or any other similarly suitable means. In this case, the control signal may be encoded by the control circuitry such that the selected at least one visible illumination characteristic is modulated for signaling the presence of the moving object. Accordingly, it is possible to further improve the illumination quality. Actually more than a 'follow-me' behavior is reached in this way. 'Follow-me' can be realized by simple (of-the-shelf) luminaires with a presence detector: all lights at places where you have been are on. However, the proposed set-up will also have an impact at places you have not been. This leads to a guide-me' behavior. Accordingly, it is possible to provide a more pleasant illumination by providing a "guide me" behavior. For example, it may be possible arrange the illumination to follow an object without having to for example use switches. In alternative embodiments the light output could be changed gradually to avoid rapid changes if there are several people moving in the surrounding. Also, it may be possible to include a time delay wherein the inventive control device detects an illumination characteristic and only starts to send a responsive illumination characteristic after some time delay (which for example may depend on the detected illumination characteristic). In this way it may be possible to send a "wave of light" through a street and/or corridor without somebody being present. Also, in an alternative embodiment the light output could be changed gradually to avoid rapid changes if there are several objects (e.g. people or vehicles) moving in the spaces.

Different types of visible light illumination characteristics may be provided, including for example emission of light having a predetermined intensity, emission of light having a predetermined color, and/or emission of light having a predetermined beam width. Accordingly, as an example it may be possible to detect red light and emit blue light. Furthermore, the control circuitry may be equipped with additional functionality for further improving the illumination quality, for example by logging previously selected visible light illumination characteristics and use them in the selection of a present at least one visible light illumination characteristic. From a general perspective the illumination characteristics may include flood lighting, indirect lighting, and multiple spot lighting. The control device may be provided as a separate unit, but may also be incorporated in with a luminaire or included in the lamp socket. Also, to achieve a high energy efficiency the light source is preferably selected from a group comprising light emitting diodes (LEDs), organic light emitting diodes (OLEDs), polymeric light emitting diodes (PLEDs), inorganic LEDs, cold cathode fluorescent lamps (CCFLs), hot cathode fluorescent lamps (HCFLs), plasma lamps. As mentioned above, LEDs have much higher energy efficiency in comparison to conventional light bulbs which generally deliver at best about 6% of their electric power used in the form of light. The skilled person would appreciate that it of course would be possible to use a standard incandescent light source, such as an argon, krypton, and/or xenon light source. In an even more preferred embodiment, the light source may for example comprise a combination of at least some of red, green, blue, yellow, magenta and cyan LEDs for creating mixed color lighting. It is however also possible to use one or a plurality of white LEDs. Further combinations are also possible.

The luminaire may also further comprise means for adjusting the beam width of light emitted by the visible illumination light source, possibly controlled by means of the control circuitry based on the selected illumination characteristic. Furthermore and as discussed above, a plurality of control devices may be arranged such that thereto connected illumination devices are made aware of each other's state. As such it is possible to provide a lighting system comprising a plurality of luminaires each comprising an inventive control device.

According to another aspect of the invention, there is provided a method for controlling a visible illumination light source, comprising detecting a visible light illumination characteristic, selecting at least one of a number of predetermined visible light illumination characteristics, and providing a control signal corresponding to the at least one selected illumination characteristic for controlling the illumination light source, wherein the at least one selected visible illumination characteristic is different than the illumination characteristic detected by the light sensor.

By means of this aspect of the present invention it is, in a similar and analogue way as described above with reference to the first aspect of the invention, possible to further decreased energy consumption as well as an improvement of the illumination quality without having to reside to complex and expensive RF communication techniques.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled addressee realize that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The various aspects of the invention, including its particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings, in which:

Fig. 1 is a block diagram of a luminaire according to a currently preferred embodiment of the present invention; and Fig. 2a - b and 3a - b illustrate the operation of a lighting system according to a currently preferred embodiment of the present invention.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled addressee. Like reference characters refer to like elements throughout.

Referring now to the drawings and to figure 1 in particular, there is depicted a block diagram of a luminaire 100 according to an embodiment of the present invention. The luminaire 100 comprises a control device 102 and a visible illumination light source 104. As discussed above, the illumination light source may for example be selected from a group comprising light emitting diodes (LEDs), organic light emitting diodes (OLEDs), polymeric light emitting diodes (PLEDs), inorganic LEDs. For emission of white light, a white light emitting LED may be used, as well as a plurality of differently colored LEDs together producing white light, or for example a phosphor coated blue LED producing essentially white light. The control device 102 comprises control circuitry 106. The control circuitry

106 may include a microprocessor, microcontroller, programmable digital signal processor or another programmable device. The control circuitry 106 may also, or instead, include an application specific integrated circuit, a programmable gate array programmable array logic, a programmable logic device, or a digital signal processor. Where the control circuitry 106 includes a programmable device such as the microprocessor or microcontroller mentioned above, the processor may further include computer executable code that controls operation of the programmable device.

Additionally, the control device 102 comprises a first sensor 108 for detecting lighting changes in the surrounding of the luminaire 100 and a second sensor 110 for detecting a moving object, such as a moving person and/or a moving car, in the surrounding of the luminaire 100. Outputs from the first 108 and the second 110 sensors are provided to the control circuitry 106. The first sensor 108 may be a photo diode, while the second sensor 110 may be a sensor using IR, ultrasound or any other similarly suitable means providing similar functionality for detecting the moving object in a surrounding area of the control device 102. The area may for example be about as large as the area that is directly illuminated by the luminaire 100. Instead of using the second sensor 110, the control circuitry may be adapted for receiving information from for example a camera (not shown) in regards to a moving object. In figure 1, the control device 102 is discussed as comprised in the luminaire 100. However, the functionality provided by the control device 102 may also be mounted between the visible illumination light source 104 and for example a lamp socket (not shown). The control device 102 may also comprise a driver 112 for controlling the light emitted by the illumination light source 104. Such a driver may receive a voltage signal 114 from the mains and adjust it such that it to a drive signal 116 suitable for driving the illumination light source 104.

Turning now to Fig. 2, which illustrates a first operational scenario of a lighting system 200 comprising five luminaires 100a - 10Oe. The lighting system 200 may of course comprise more or less than five luminaires 100. In Fig. 2a, a person 202 is moving along a corridor in which the luminaires 100a - lOOe are arranged. As discussed above, each of the luminaires 100a - lOOe comprises an inventive control device 102 and at least one visible illumination light source 104. At one point in time, the person 202 has moved such that he/she is below luminaire 100 c and detected. The luminaire 100c provides in this case light having a first light characteristic, for example where the luminaire 100c emits white light having a maximum intensity level. As a result, the luminaires 100b and lOOd arranged in a relatively close surrounding of the luminaire 100c detects the light of luminaire 100c and respond with for example, but not limited to, a different light illumination characteristic, for example light having an intensity level that is lower than the intensity level for the light emitted by the luminaire 100c. Consequently, luminaires 100a and lOOe detect the light of luminaire 100b and lOOd and in turn respond with still different light characteristics (e.g. by emitting light having an even lower intensity level).

If the person 202 moves in a direction closer towards the luminaire lOOd (as is illustrated in Fig 2b), he/she may not only be detected by luminaire 100c, but also by luminaire 10Od. In a response to this, luminaire lOOd may for example increase its light intensity level to an intensity level similar to the one emitted by the luminaire 100c. Consequently, luminaire lOOe responds to the changed illumination characteristics provided by the luminaire 10Od, and thus also changes its lighting characteristics, for example by also increasing the intensity level provided. If the person 202 moves further in the same direction (i.e. towards luminaire 10Oe) there may be an additional shift of intensity level in a manner similar to the one just descried. In a preferred embodiment the intensity level of the luminaire 100 becomes smaller as the distance to the person 202 increases, thereby illustrating the above discussed "guide me" feature made possible by means of the invention.

In another preferred embodiment, aimed at e.g. outdoor illumination, the intensity level has a lower bound, to avoid frightening dark areas. Also, the first sensor 108 may be used to let a minimum intensity level of light emitted by the luminaire 100 dependent on the background illumination level (which for example may arise due to changes in daylight). In this way the system 200 can save even more energy. Additionally, if more than one luminaire 100 detects the presence of a person 200, all luminaires 100 detecting persons may be arranged to emit light having a maximum intensity level.

For easily communicating a specific illumination characteristic, the light emitted by each of the luminaires 100a - lOOe may be coded as described below. The coded visible light will then in turn be detected by a luminaire 100 in the surrounding of the luminaire 100 emitting the coded light (e.g. similar to PWM). In an embodiment a frequency modulation of the emitted light is used of communicating illumination characteristic. For example, if the presence of one or more persons is detected the light emitted by one luminaire 100 may for instance varied with a frequency f. If there is no presence detected, but only light from neighboring luminaires 100, the highest frequency in this light may be doubled or more generally modulated at a second unique frequency. Instead of doubling of the frequencies it may be useful to make use a small list of unique frequencies. The advantage of this, compared to doubling frequencies, is that the change of a wrongly assigning frequency is smaller as beat frequencies or harmonic frequencies are not part of the list and can be disregarded automatically. In one exemplary implementation a set of frequencies may be selected, e.g. fl, f2, O, fx. It should be noted that the frequencies fl, f2, O can be any frequency e.g. 10 kHz, 130 kHz, 7.4 kHz. The luminaire that detect a moving object will emit light with frequency fl independent of any detected light. A luminaire that does not detect an object searches for any light with frequencies fl, f2, O, fx. It will emit light with a frequency ranked one below the highest-ranking detected frequency e.g. if it detects fl and f2 it will emit f2. For example, if it only detects f2 it will emit O. Accordingly, all luminaires within a detecting range of a specific luminaire 100 emitting modulated with frequency fl will start emitting light modulated with frequency f2. Also, if a luminaire 100 detects light being modulated by the same frequency as currently used it will cause that luminaire to switch to a lower ranking modulation frequency, possibly giving a lower intensity level, meaning if no other light is active it will automatically switch off after a few alterations. Furthermore the light output of the luminaire is a function of the frequency at which it is modulated. In a preferred embodiment the lamp with the lowest frequency results in the highest light output. If the detected light has a frequency above a certain frequency fmax, the resulting light output is zero or fixed at a certain level. In the latter case a minimum amount of illumination is guaranteed.

Additionally, in Fig 3 a second operational scenario of a lighting system 200 is provided. Similarly to Fig 2, the lighting system 200 comprises a plurality of luminaires 100, however in Fig. 3 a and 3b it is illustrated the case if the person 202 moves from a first room to a second room by opening a door. In Fig. 3a the person 202 is in the first room and is only detected by luminaire 100c. Luminaires 100a and 100b respond as described above in relation to Fig 2. Luminaires lOOd and lOOe do not detect anything (due to the door that is closed) and hence do not respond. However, if the person 202 opens the door (see Fig 3b.), luminaire lOOd detects the light of luminaire 100c, and luminaire lOOd responds with emitting light having a predetermined illumination characteristic corresponding to the detected illumination characteristic. Consequently, and as is discussed in relation to Fig. 2, the luminaire lOOe will respond to the illumination characteristic emitted by the luminaire 10Od. Furthermore, if the person 202 continues to move, and thus moves into the second room and closes the door, the luminaires 100a, 100b and 100c may be switched off, or possibly reduces their light output to a predefined minimum level.

Even though the invention has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art. For example, the control circuitry 106 may include storage means for storing previously selected illumination characteristic. That is, if a luminaire 100 reacted with a specific illumination characteristic it may be adapted to later on change its illumination characteristic to another different illumination characteristic (e.g. leading to a stepwise or continuously variable change in the intensity level of light emitted by the luminaire 100). Also, the detected illumination characteristic indicates that the object is moving away from the luminaire 100, it may thus be arranged such that the intensity level of light emitted by the luminaire 100 decreases faster that in a normal speed of decreasing intensity level. Furthermore, a luminaire 100 may go blind (numb) for a predefined period of time such that it enables proper switch off of a self-containing sequence. Variations to the disclosed embodiments can be understood and effected by the skilled addressee in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

Claims

CLAIMS:

1. A control device (102) for an illumination light source (104), comprising: a light sensor (108) for detecting a visible light illumination characteristic; and control circuitry (106) adapted to select at least one of a number of predetermined visible light illumination characteristics based on a signal received from the light sensor (108) and to output a control signal corresponding to the at least one selected illumination characteristic for controlling the illumination light source (104).

2. Control device according to claim 1, wherein the at least one selected visible illumination characteristic is different from the illumination characteristic detected by the light sensor.

3. Control device according to claim 1 or 2, wherein the control signal is encoded by the control circuitry such that the selected at least one visible illumination characteristic is modulated to comprise a frequency component.

4. Control device according to any one of the preceding claims, further comprising a sensor for detecting the presence of a moving object in a surrounding of the control device.

5. Control device according to claim 4, wherein the control signal is encoded by the control circuitry such that the selected at least one visible illumination characteristic is modulated for signaling the moving object.

6. Control device according to any one of the preceding claims, wherein the at least one predetermined visible light illumination characteristics are selected from a group comprising: emission of light having a predetermined intensity; emission of light having a predetermined color; and emission of light having a predetermined beam width.

7. Control device according to any one of the preceding claims, wherein previously selected visible light illumination characteristics are logged and used by the control circuitry for selecting a present at least one visible light illumination characteristic.

8. Luminaire, comprising a visible illumination light source and a control device according to any one of claims 1 - 7.

9. Luminaire according to claim 8, wherein the visible illumination light source comprises at least a light emitting diode (LED).

10. Luminaire according to claim 8 or 9, further comprising means for adjusting the beam width of light emitted by the visible illumination light source.

11. Lighting system, comprising a plurality of luminaires according to any one of claims 8 - 10.

12. A method for controlling a visible illumination light source, comprising: detecting a visible light illumination characteristic; - selecting at least one of a number of predetermined visible light illumination characteristics; and providing a control signal corresponding to the at least one selected illumination characteristic for controlling the illumination light source.

13. Method according to claim 12, wherein the at least one selected visible illumination characteristic is different from the illumination characteristic detected by the light sensor.

14. Method according to claim 12 or 13, further comprising: - encoding the control signal such that the selected at least one visible illumination characteristic is modulated to comprise a frequency component.

15. Method according to any one of claims 12 - 14, further comprising: detecting the presence of a person; and encoding the control signal such that the selected at least one visible illumination characteristic is modulated for signaling the presence of the person.