DE102013103692B4 - A method of generating and light source for providing color changing light - Google Patents

Abstract

A method of producing color-changing light in which n light components provided by n different illuminants (2) and differing in wavelengths are superposed on the light changing in color, and in the light intensities Ai (t) with i = 1,..., n of the n light components provided by the n illuminants (2) are controlled in such a way that they change with time t, characterized in that the light intensity Ai (t) of the i a light component is periodically modulated over the time t with a frequency ωi associated with the i-th light component according to Ai (t) = Bi + Mi · sin (ωit + φi), where Bi is a DC component, Mi is a modulation amplitude and φi is a phase and wherein the ratio of the frequencies ωi assigned to the different light components is a number which is at least so close to an irrational number that a color gradient (6) of the color changes light in each period within a given period of time is different from any other period within the given period of time, and where the number of irrational numbers is closer, the longer the predetermined period of time.

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to a method for producing light which changes color. Furthermore, the invention relates to a light source for providing color changing light.

STATE OF THE ART

Colored light, the color of which is variable, is usually generated by superimposing light components which differ in their wavelength and thus in their color (additive color mixing). By changing the light components with respect to their light intensity, the color of the colored light can then be varied. Typically, three different bulbs are used to provide light components with the primary colors red, green and blue. By superposing the three primary colors, each with the same intensity, the color of the resulting colored light is white. If the light intensity of one of the light components changes, the color of the colored light changes. If the three light components are continuously changeable in their light intensity, the color of the colored light can be changed over the entire RGB color spectrum.

An apparatus for generating color changing light is, for example, from the document DE 20 2004 020 727 U1 known. The device has three light sources that provide red, green and blue light. For each light source a free oscillating oscillator is provided, is controlled with the light source such that the light intensity of the light provided is periodically modulated. The oscillators for the different light sources have mutually different frequencies, none of the frequencies being an integer multiple of one of the other two frequencies.

From the document DE 299 20 603 U1 It is known to use for generating color changing light three bulbs that provide light in the primary colors red, green and blue, wherein the light intensities of the light provided by pulse width modulation of the lighting-driving signals are varied.

OBJECT OF THE INVENTION

The invention has for its object to provide a method of generating or a light source for providing color changing light, in which or at each period within a period of time in which the light changes in color, by a Color gradient of changing in its color light is clearly determinable.

SOLUTION

The object of the invention is achieved according to the invention with the features of the independent claims 1 and 5. Further preferred embodiments according to the invention can be found in the dependent claims.

DESCRIPTION OF THE INVENTION

The invention relates to a method for producing light which changes color. For this purpose, n light components, which are provided by n different light sources and differ in their wavelengths, are superimposed to the light changing in its color. By changing the different light components in their light intensities A _i (t) with i = 1, ..., n with time t, the light generated by their superimposition changes in color over time t. In the method according to the invention, the light intensities A _i (t) do not change randomly with the time t, but the light intensity A _i (t) of the ith light component is adjusted over the time t with a frequency ω _i assigned to the ith light component A _i (t) = B _i + M _i · sin (ω _i t + φ _i ) periodically modulated. By modulating the light intensities periodically, there are no cracks in a color gradient of the light changing in color, but its color changes continuously over time t. This results in a kind of "continuous" color gradient.

If the ratio of the frequencies ω _{i is} an irrational number, the color gradient of the light changing in color is different in each period within an infinitely long period of time than in any other period within that infinitely long period of time. That is, no repetitions in the color gradient occur over an infinitely long period of time. For a finite period of time, it is not necessary to exclude repetitions beyond the predetermined finite length of time. In this case, the ratio of the frequencies ω _i need not be an irrational number, but it is sufficient that the ratio of the frequencies ω _i is a number sufficiently close to an irrational number so that the color of the light changing in color is different in each time period within the given finite time period than in any other time period within the given finite time span. It can therefore be achieved by suitable choice of the ratios of the different light components associated frequencies ω _i , that each period within a period of time in which the light changes in color on clearly associated with a color gradient of changing color in its light.

How close the number of irrational numbers must be depends on the length of the given period of time. According to the invention, it is therefore provided that the number of irrational numbers comes closer the longer the predetermined period of time. For example, this can be done by further approximating the number by lengthening the predetermined period of time by successively taking into account further decimal places of the irrational numbers.

The choice of frequencies determines how the light changes its color. In particular, it specifies how fast and in which color sequence the light changes its color. If the frequency ω _{i of} the i-th light component is increased, this means that the light intensity of the i-th light component changes faster. On the one hand, this results in a different color gradient for the light changing in its color. On the other hand, the color change of the color changing light is faster. If all ω _i , with which the light intensities A _i (t) of the different light components are modulated, are changed by one and the same factor, the speed with which the light changes its color changes while the color gradient remains constant.

Via the phases φ _{i of} the various light components, an initial state, from which the light changes its color, can be defined. Consequently, by changing one or more phases φ _i, the initial state can be set in a targeted manner. When the phase φ _{i of} the i-th light component is changed by an amount other than an integer multiple of 2π, another coloration results from the set initial state besides another initial state.

About the DC component B _i and the modulation amplitude M _i a minimum value and a maximum value of the light intensity of the ith light component are set, between which the light intensity is periodically varied. Accordingly, it is determined via these values to what proportion the i-th light component can contribute to the color-changing light to a maximum or minimum. The DC component B _i is matched to the modulation amplitude M _i in such a way that the light intensity can not assume a negative value. By changing the DC component B _i and / or the modulation amplitude M _i of at least one of the n light components, it is thus possible to set a color space over which the light changes its color. An increase in the modulation amplitude M _{i in} this case means an enlargement of the color space. The DC component B _i must be adapted accordingly so that it is ensured that the light intensity does not assume a negative value.

Furthermore, the invention relates to a light source for providing color changing light. The light source has n light sources which together provide n light components of different wavelengths, the n light components being superimposed on the light changing color provided by the light source. Furthermore, the light source according to the invention has a control device which changes the light intensities A _i (t) with i = 1,..., N of the n light components provided by the n light means with the time t. In this case, the control device modulates the light intensity A _i (t) of the ith light component over time with a frequency ω _i assigned to the ith light component _in accordance with a sinusoidal profile A _i (t) = B _i + M _i · sin (ω _i t + φ _i ). As in the method according to the invention, B _{i is} a DC component, M _{i is} a modulation amplitude and φ _{i is} a phase associated with the ith light component. In order to prevent a color gradient from repeating over a given period of time, the ratio of the frequencies ω _{i associated with} the various light components is a number at least as close to an irrational number that a color gradient of the light changing in color is present in each Period within a given period of time is different than in any other period within the given period of time. This ensures that the light components overlap each other over the predetermined period of time to different proportions, whereby a constantly changing over the predetermined period of color gradient is achieved. By the light intensities of the light components are periodically modulated, no jumps occur in the color gradient, but the light changes steadily in its color.

The lighting means can basically be configured as desired. The light source may, for example, comprise a single light-emitting element, the emitted light covering a broad wavelength range. To provide the n different light components differing in their wavelengths, the light source can have n wavelength filters, the wavelength filters each allowing light of different wavelengths or wavelength ranges to pass through. However, it is also possible to provide a separate light-emitting element for each of the n light sources of the light source, the elements each emitting light of different wavelengths. In particular, the lighting means of the light source can be light-emitting diodes. These are characterized by high energy efficiency and easy controllability.

If the light source has at least one red, one green and one blue light emitting diode, the color of the light changing in color can be changed over the entire RGB color spectrum.

A change in the light intensities can be achieved, for example, by periodically modulating a current for the electrical supply of the light-emitting diodes. Since light emitting diodes typically can be operated stably only over a limited current range, however, it is preferably provided that the control device controls the light intensities by pulse width modulation of the signals driving the light emitting diodes.

Advantageous developments of the invention will become apparent from the claims, the description and the drawings. The advantages of features and of combinations of several features mentioned in the description are merely exemplary and can take effect alternatively or cumulatively, without the advantages having to be achieved by embodiments according to the invention. Without thereby altering the subject matter of the appended claims, as regards the disclosure of the original application documents and the patent, further features can be found in the drawings, in particular the illustrated geometries and the relative dimensions of several components and their relative arrangement and operative connection. The combination of features of different embodiments of the invention or of features of different claims is also possible deviating from the chosen relationships of the claims and is hereby stimulated. This also applies to those features which are shown in separate drawings or are mentioned in their description. These features can also be combined with features of different claims. Likewise, in the claims listed features for further embodiments of the invention can be omitted. The features mentioned in the patent claims and the description are to be understood in terms of their number that exactly this number or a greater number than the said number is present, without requiring an explicit use of the adverb "at least". For example, when talking about an element, it should be understood that there is exactly one element, two elements or more elements. These features may be supplemented by other features or be the only characteristics that make up the product in question. The reference numerals contained in the claims do not limit the scope of the objects protected by the claims. They are for the sole purpose of making the claims easier to understand.

BRIEF DESCRIPTION OF THE FIGURES

In the following the invention will be further explained and described with reference to preferred embodiments shown in the figures.

1 shows a light source according to the invention.

2 shows an exemplary color gradient for changing in its color light of two light components.

3 shows an exemplary color gradient for changing in its color light from three different light components.

DESCRIPTION OF THE FIGURES

1 shows a light source according to the invention 1 for providing light changing in color with four bulbs 2 which together provide four light components of different wavelengths to that of the light source 1 provided with light changing in its color. For each of the bulbs 2 is a utility 3 provided, which is a signal for driving the respective supply device 3 associated light source 2 provides. Furthermore, the light source 1 a control device 4 for controlling light intensities of the light sources 2 provided light components. For electrical supply of utilities 3 and the controller 4 is at the in 1 illustrated embodiment, a power supply 5 intended.

For example, it can be at the utilities 3 to act constant current sources, which is a constant current signal to drive the bulbs 2 provide. Controlling the light intensities by means of the control device 4 can then by pulse width modulation of the utilities 3 provided the bulbs 2 triggering constant current signals.

To deal with the light source 1 To provide changing in its color light, the light intensities of the light components of the bulbs 2 periodically modulated. In this case, every light component, ie each light source 2 , a frequency ω _{i associated} with i = 1, 2, 3, 4, with the light intensity A _i (t) according to A _i (t) = B _i + M _i · sin (ω _i t + φ _i ) is modulated , In this case, a minimum and a maximum value of the light intensity A _i (t) are set via a DC component B _i and a modulation amplitude M _i , between which the light intensity is varied. Via a phase φ _i , an initial value of the light intensity A _i (t = 0) is set. By modulating the light intensities of the light components over time t, the light components over time t contribute different levels to that of the light source 1 provided light, which changes the light in its color. The sinusoidal modulation of the light intensities ensures that no color jumps occur. The fact that a color gradient of the color changing light does not repeat within a given period of time is achieved by the ratio of the frequencies ω _i assigned to the different light components being a number which comes so close to an irrational number that the color gradient in each period is different within the given time period than in any other period of the given period of time. In this case, the closer the number of irrational numbers comes to, the longer the predetermined time span can be. Ideally, the number is an irrational number, which ensures that there are no repetitions over an infinite period of time. For a rational number, on the other hand, there is a closed color gradient, ie after finite time, a color sequence is repeated. The finite time after which a repetition of the color sequence occurs is determined by the smallest common multiple of the frequencies ω _{i of} the different light components.

In 2 is an exemplary gradient 6 represented by changing in its color light, which is generated by the superposition of two light components of different wavelengths, for which the light intensities A ₁ (t), A ₂ (t) of the two light components are plotted against each other. At the in 2 example shown is the ratio of the two light components associated frequencies ω ₁ / ω ₂ = 2/3. For the DC components B _i , the modulation amplitudes M _i and the phases φ _i , the same values are assumed for both light components. For the color gradient 6 This results in a so-called closed Lissajous figure, ie the color gradient is repeated after a period of time which is predetermined by the smallest common multiple of the frequencies ω _i assigned to the two light components. At the in 2 As shown, the color gradient repeats after six units of time. It is thus for a predetermined period of time, which is less than six units of time, ensures that each period within the predetermined period of time in a unique way a color gradient is assigned.

In order to be able to ensure over a longer period of time that no repetitions occur, the ratio of the frequencies allocated to the two light components is chosen such that the ratio is a number that approximates an irrational number. It can also be supplemented with another light component, which is superimposed with the other light components to the changing color in the lights. The further light components result in a further dimension in which the light can change its color.

In 3 is a gradient 6 for the changing in its color light in which three light components are superimposed to the changing color in its light. Accordingly, a three-dimensional curve results when the light intensities A ₁ (t), A ₂ (t), A ₃ (t) of the light components are plotted against each other.

LIST OF REFERENCE NUMBERS

1

light source

2

Lamp

3

supply

4

control device

5

power supply

6

color gradient

A ₁ (t)

Light intensity

A ₂ (t)

Light intensity

A ₃ (t)

Light intensity

Claims (8)

Method for producing light which changes in color, in which n light components, which differ from n different light sources ( 2 ) and which differ in their wavelengths to which light whose color changes are superimposed, and in which light intensities A _i (t) with i = 1,..., n of the n illuminants ( 2 ) light components are controlled such that they change with time t, characterized in that the light intensity A _i (t) of the i-th light component over the time t with a i-th light component associated frequency ω _i according to A _i (t) = B _i + M _i * sin (ω _i t + φ _i ) is periodically modulated, where B _{i is} a DC component, M _{i is} a modulation amplitude and φ _{i is} a phase and wherein the ratio of the frequencies associated with the different light components ω _{i is} a number that is at least as close to an irrational number that a color gradient ( 6 ) of the color changing light is different in each period within a predetermined period of time than in any other period within the predetermined period, and the longer the predetermined period of time, the closer the number of the irrational number becomes. A method according to claim 2, characterized in that all ω _i , with which the light intensities A _i (t) of the different light components are modulated by one and the same factor changed to set a speed at which the light changes color. Method according to one of the preceding claims, characterized in that at least one phase φ _{i is} changed in order to set an initial state, from which the light changes its color. Method according to one of the preceding claims, characterized in that at least one of the n light components of the DC component B _i and / or the modulation amplitude M _{i are} changed in order to set a color space over which the light changes its color. Light source ( 1 ) for providing light changing in color with light bulbs ( 2 ) which together provide n light components of different wavelengths, the n light components being superimposed to the provided light, and - a control device ( 4 ), the light intensities A _i (t) with i = 1,..., n of the n light sources ( 2 ) light components with the time t changes, characterized in that the control device ( 4 ) the light intensity A _i (t) of the ith light component over the time t with a frequency ω _{i associated} with the i-th light component according to A _i (t) = B _i + M _i · sin (ω _i t + φ _i ) where B _{i is} a DC component, M _{i is} a modulation amplitude and φ _{i is} a phase, and wherein the ratio of the frequencies ω _i assigned to the different light components is at least as close to an irrational number that a color gradient ( 6 ) of the color changing light is different in each period within a predetermined period of time than in any other period within the predetermined period of time, with the number of irrational numbers coming closer, the longer the predetermined period of time. Light source ( 1 ) according to claim 5, characterized in that the lighting means ( 2 ) Are light-emitting diodes. Light source ( 1 ) according to claim 6, characterized in that the light source ( 1 ) has at least one red, one green and one blue light emitting diode. Light source ( 1 ) according to one of claims 6 or 7, characterized in that the control device ( 4 ) controls the light intensities by pulse width modulation of the LEDs driving signals.

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