WO2021239575A1

WO2021239575A1 - Lighting device and method for driving a lighting device

Info

Publication number: WO2021239575A1
Application number: PCT/EP2021/063467
Authority: WO
Inventors: Tilman Ruegheimer; Hubert Halbritter; Ann RUSSELL
Original assignee: Osram Opto Semiconductors Gmbh
Priority date: 2020-05-27
Filing date: 2021-05-20
Publication date: 2021-12-02

Abstract

The present disclosure provides a lighting device (1) for emitting light of variable colour or colour temperature, wherein the lighting device (1) comprises at least a first light emitting device (2), which is provided to emit light of a first colour or first colour temperature (L1), and comprises at least a second light emitting device (3), which is provided to emit light of a second colour or second colour temperature (L2), and comprises a control unit (4), which comprises a control device (5), wherein the control device (5) comprises a control element (6) and a signal processing element (7) for receiving an external time signal (S1) and for providing a time-dependent control signal (S2) to the control element (6), and wherein the control element (6) is provided for driving the first light emitting device (2) and the second light emitting device (3) in a time-dependent way such that the colour or colour temperature of the light emitted by the lighting device (1) is variable over time. Furthermore, the present disclosure provides a method for driving a lighting device (1).

Description

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Description

LIGHTING DEVICE AND METHOD FOR DRIVING A LIGHTING DEVICE

BACKGROUND

1. Technical Field

The present disclosure generally relates to a lighting device and a method for driving the lighting device, and more particularly, to a human centric lighting device and method for driving the same.

2. Description of Related Art

There are lamps having a fixed color temperature. If you want to tune e.g. from cold to warm white, you need to switch lamps, for example via remote control, apps or wifi connection .

SUMMARY

Accordingly, the present disclosure is directed to a lighting device and a method for driving the same, which allow for user-independent, automatic day/night time color temperature control/switching.

The present disclosure provides a lighting device for emitting light of variable colour or colour temperature, wherein the lighting device comprises at least a first light emitting device, which is provided to emit light of a first colour or first colour temperature, and comprises at least a second light emitting device, which is provided to emit light 2019PF03622 May 20, 2021

WO 2021/239575 ^FPCT/EP2021/063467 ^N 2 of a second colour or second colour temperature, and comprises a control unit, which comprises a control device, wherein the control device comprises a control element and a signal processing element for receiving an external time signal and for providing a time-dependent control signal to the control element, and wherein the control element is provided for driving the first light emitting device and the second light emitting device in a time-dependent way such that the colour or colour temperature of the light emitted by the lighting device is variable over time.

In particular, the external time signal is an already available time signal. So, the use of the already available time signal within the lighting device allows to distribute power between the first and the second light emitting devices .

Preferably, the first and second light emitting devices are semiconductor devices, most preferably light emitting diodes.

According to an embodiment of the present disclosure, the light emitted by the lighting device is variable at least between the first colour or first colour temperature and the second colour or second colour temperature.

According to an embodiment of the present disclosure, the external time signal is at least one of the following signals: a universal time signal, a mobile phone signal, an energy net signal, a ripple control signal.

According to an embodiment of the present disclosure, the control unit comprises a storage device for storing electrical energy, which is provided to supply electrical 2019PF03622 May 20, 2021

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3 energy to the control device. In particular, the storage device comprises at least one of the following: a battery, a capacitor .

According to an embodiment of the present disclosure, the control unit comprises an interface device for configuration of the lighting device by a user.

According to an embodiment of the present disclosure, the first colour temperature is cold-white and the second colour temperature is warm-white.

Furthermore, the present disclosure provides a method for driving a lighting device, especially according to the above mentioned embodiments, comprising the following steps:

- receiving an external time signal and providing a time- dependent control signal from the signal processing element to the control element,

- driving the first light emitting device and the second light emitting device in a time-dependent way by the control element such that the lighting device emits light with a colour or colour temperature, which is variable over time.

According to an embodiment of the present disclosure, during a first time period the first light emitting device and the second light emitting device are driven in such a way that a current through the first light emitting device is higher than a current through the second light emitting device.

According to an embodiment of the present disclosure, during a second time period the first light emitting device and the second light emitting device are driven in such a way that a 2019PF03622 May 20, 2021

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4 current through the first light emitting device is lower than a current through the second light emitting device.

Preferably, the lighting device emits light close or equal to the first colour or first colour temperature during the first time period. And the lighting device emits light close or equal to the second colour or second colour temperature during the second time period.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.

Fig. 1 is a schematic illustration of a lighting device according to one embodiment.

Fig. 2A and Fig. 2B show current distributions of first and second light emitting devices according to a first embodiment of a method for driving a lighting device.

Fig. 3A and Fig. 3B show current distributions of first and second light emitting devices according to a second embodiment of a method for driving a lighting device.

Fig. 4A and Fig. 4B show duty cycle distributions of first and second light emitting devices according to a third embodiment of a method for driving a lighting device. 2019PF03622 May 20, 2021

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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferred embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

FIG. 1 shows a lighting device 1 for emitting light of variable colour or colour temperature. The lighting device 1 comprises a first light emitting device 2, which is provided to emit light LI of a first colour or first colour temperature, especially cold white light. Moreover, the lighting device 1 comprises a second light emitting device 3, which is provided to emit light L2 of a second colour or second colour temperature, especially warm white light. Furthermore, the lighting device 1 comprises a control unit 4.

The control unit 4 itself comprises a control device 5, wherein the control device 5 comprises a control element 6 and a signal processing element 7 for receiving an external time signal SI and providing a time-dependent control signal S2 to the control element 6. The control element 6 is provided for driving the first light emitting device 2 and the second light emitting device 3 in a time-dependent way such that the colour or colour temperature of the light emitted by the lighting device is variable over time. The control element 6 may comprise or consist of a switch, for example a transistor or field effect transistor. 2019PF03622 May 20, 2021

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The control unit 4 may comprise a storage device 8 for storing electrical energy, which is provided to supply electrical energy to the control device 5. In particular, the storage device 8 comprises at least one of the following: a battery, a capacitor. By means of the storage device 8, the signal processing element 7 may be ready to receive an external time signal SI and provide a time-dependent control signal S2 just when the lighting device 1 is switched on. The storage device 8 can be recharged when line-power is on or by wireless charging.

The control unit 4 may comprise an interface device 9 for configuration of the lighting device 1 by a user. In particular, the interface device 9 may comprise at least one, preferably small switch where a user can disable default settings or choose individual settings. For example, per default the switching might take place around 8 PM to warm and 7 AM to cold. Moreover, the user might shift the switching time by e.g. X hours to adapt better to his local time.

A first embodiment of a method for driving a lighting device, especially the lighting device as shown in Fig. 1, is described in connection with Fig. 1, Fig. 2A and Fig. 2B.

First, an external time signal SI is received by the signal processing element 7. The external time signal SI may be a universal time signal received from the "Physikalisch- Technische Bundesanstalt" (abbrev. PTB). Moreover, the external time signal SI may be a mobile phone signal coming from the user's mobile phone, for example. 2019PF03622 May 20, 2021

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Furthermore, the external time signal SI may be a ripple control signal, which

- can be provided as a service from an energy supplier or

- can be set by an individual home owner for his house, e.g. similar to smart home, by a small box with electronics in the basement, for example, or as a plug with small electronics put into any power outlet within the house or

- can be provided by powerline.

According to at least one embodiment, time will be reset/ synchronized periodically and automatically based on the external time signal SI without any command of the user. Preferably, there is an internal counter (not shown) in the lighting device 1 which runs once it is triggered.

A time-dependent control signal S2 is provided from the signal processing element 7 to the control element 6, and the first light emitting device 2 and the second light emitting device 3 are driven in a time-dependent way by the control device 5 or control element 6 such that the lighting device 1 emits light with a colour or colour temperature, which is variable over time.

For example, the control element 6 may comprise or consist of a switch, which provides a digital (on/off) or soft (gradual) switching of the first and second light emitting devices 2, 3 dependent on the time-dependent control signal S2.

In the first embodiment as shown in Fig. 2A and Fig. 2B, the switching of the first and second light emitting devices 2, 3 is digital, which means that a current I flowing through the first and second light emitting devices 2, 3 changes abruptly over time t. 2019PF03622 May 20, 2021

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For example, at point tO, which may correspond to 0 o'clock, the current I flowing through the first light emitting device 2 is low, but increases abruptly at point tl, which may correspond to 6 AM, and decreases abruptly at point t2, which may correspond to 6 PM, and then stays the same until t3, which may correspond to 11:59 PM (see Fig. 2A).

Moreover, at point tO, the current I flowing through the second light emitting device 3 is high, but decreases abruptly at point tl and increases abruptly at point t2, and then stays the same until t3 (see Fig. 2B).

Especially, the currents I flowing through the first and second light emitting devices 2, 3 are complementary to each other.

In other words, during a first time period t2 - tl, that is between tl and t2, the first light emitting device and the second light emitting device 2, 3 are driven in such a way that a current I through the first light emitting device 2 is higher than a current I through the second light emitting device 3. Moreover, during a second, for example complementary, time period tl - t2, that is for example between t2 of the preceding day and tl, the first light emitting device 2 and the second light emitting device 3 are driven in such a way that a current I through the first light emitting device 2 is lower than a current I through the second light emitting device 3. As a consequence, the lighting device 1 may emit light close or equal to the first colour or first colour temperature during the first time period t2 - tl. And the lighting device 1 may emit light close or equal to the second colour or second colour temperature during the second, for example complementary time 2019PF03622 May 20, 2021

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9 period tl - t2. Especially, the lighting device 1 emits cold- white light during day-time and warm-white light during night-time .

The setting of points tO, tl, t2 and t3 or of the time periods can be fix or adjustable or floating, for example depending on sunrise and sunset.

In the second embodiment shown in Fig. 3A and 3B, the switching of the first and second light emitting devices 2, 3 is soft, which means that the current I changes gradually. Hard transitions are thus avoided. The overphase period is between 1 second and 60 minutes, preferably between 1 and 30 minutes.

In the third embodiment shown in Fig. 4A and Fig. 4B, hard transitions are avoided by using pulse width modulation (PWM) and by gradually changing the duty cycle D for the first and second light emitting devices 2, 3. The overphase period is between 1 second and 60 minutes, preferably between 1 and 30 minutes. For PWM, the repetition frequency must be selected so that the eye does not perceive any flickering, which means more than 100 Hz, preferably more than 500 Hz.

It will be apparent to those skilled in the art that various modifications and variations can be made to the lighting device and method of the present disclosure without departing from the scope or spirit of the present disclosure. In view of the foregoing, it is intended that the present disclosure cover modifications and variations of the present disclosure provided they fall within the scope of the following claims and their equivalents. 2019PF03622 May 20, 2021

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This patent application claims the priority of US patent application 63/030,826, the disclosure content of which is hereby incorporated by reference.

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References

1 lighting device

2 first light emitting device

3 second light emitting device

4 control unit

5 control device

6 control element

7 signal processing element

8 storage device

9 interface device

51 external time signal

52 time-dependent control signal LI light of a first colour or first colour temperature

L2 light of a second colour or second colour temperature

Claims

2019PF03622 May 20, 2021WO 2021/239575 FPCT/EP2021/063467 N12 Claims

1. A lighting device (1) for emitting light of variable colour or colour temperature comprising

- at least a first light emitting device (2), which is provided to emit light of a first colour or first colour temperature (LI),

- at least a second light emitting device (3), which is provided to emit light of a second colour or second colour temperature (L2),

- a control unit (4), which comprises a control device (5), wherein the control device (5) comprises a control element (6) and a signal processing element (7) for receiving an external time signal (SI) and for providing a time- dependent control signal (S2) to the control element (6), wherein the control element (6) is provided for driving the first light emitting device (2) and the second light emitting device (3) in a time-dependent way such that the colour or colour temperature of the light emitted by the lighting device (1) is variable over time.

2. The lighting device (1) according to the preceding claim, wherein the light emitted by the lighting device (1) is variable at least between the first colour or first colour temperature (LI) and the second colour or second colour temperature (L2).

3. The lighting device (1) according to one of the preceding claims, wherein the external time signal (SI) is at least one of the following signals: a universal time signal, a mobile phone signal, an energy net signal, a ripple control signal. 2019PF03622 May 20, 2021

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4. The lighting device (1) according to one of the preceding claims, wherein the control unit (4) comprises a storage device (8) for storing electrical energy, which is provided to supply electrical energy to the control device (5).

5. The lighting device (1) according to the preceding claim, wherein the storage device (8) comprises at least one of the following: a battery, a capacitor.

6. The lighting device (1) according to one of the preceding claims, wherein the control unit (4) comprises an interface device (9) for configuration of the lighting device (1) by a user.

7. The lighting device (1) according to one of the preceding claims, wherein the first colour temperature (LI) is cold- white and the second colour temperature (L2) is warm-white.

8. A method for driving the lighting device (1) according to one of the preceding claims comprising the following steps:

- receiving an external time signal (SI) and providing a time-dependent control signal (S2) from the signal processing element (7) to the control element (6),

- driving the first light emitting device (2) and the second light emitting device (3) in a time-dependent way by the control element (6) such that the lighting device (1) emits light with a colour or colour temperature, which is variable over time.

9. The method according to the preceding claim, wherein during a first time period (t2 - tl) the first light emitting device (2) and the second light emitting device (3) are driven in such a way that a current (I) through the first 2019PF03622 May 20, 2021

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14 light emitting device (2) is higher than a current (I) through the second light emitting device (3).

10. The method according to one of the two preceding claims, wherein during a second time period (tl-t2) the first light emitting device (2) and the second light emitting device (3) are driven in such a way that a current (I) through the first light emitting device (2) is lower than a current (I) through the second light emitting device (3).