The present invention relates generally to a domestic refrigeration device, in particular a refrigerator, having a light source arrangement. The invention relates also to a method of controlling the light source arrangement.
In food shops, it is generally required to light the foods that are offered, such as meat, fish, fresh vegetables, cheese and bread, by means of light sources which are especially suitable therefor, in order to ensure that the foods appear as appealing as possible. It is conventional to use light sources which emit light of different spectral characteristics for different foods. For example, it is possible to use colored light sources and white light sources, but also white light sources with different correlated color temperatures, that is to say white light sources which emit, for example, a warm white with a color temperature less than 3300 K or which emit a daylight white with a color temperature greater than 5000 K. Relatively “warm” light sources are generally used for foods such as fruits, vegetables and baked goods, and relatively “cool” light sources are used for foods such as meat and fish. Since in food shops the individual foods are each presented at fixed, predetermined locations within the food shop, the individual light sources are also fixedly mounted at those locations, and nor is there any requirement to change this.
In domestic refrigeration devices too, such as in refrigerators, it is generally required that the interior of the refrigerator, in which the foods that are to be kept cool are stored, should be lit when the user opens a door of the refrigerator allowing access to the interior. The lighting is on the one hand to make it easier for the user to see the foods stored in the refrigerator, but on the other hand it is also to present the foods to the user in a particularly appealing manner. Known lighting solutions generally use fixedly positioned light sources having a specific radiation characteristic, which is independent of the type of foods being lit in the refrigerator at that time. Thus, with the known lighting solution, the foods in the refrigerator are visible but, because the lighting is independent of the foods in the refrigerator, the appearance of the lit foods is at one time more and at another time less appealing.
It is an object of the invention to eliminate disadvantages known from the prior art. In particular, it is an object of the invention to allow, in a simple and inexpensive manner, the foods stored in a domestic refrigeration device not only to be readily visible to the user of the domestic refrigeration device but also to be presented at all times with as appealing an appearance as possible.
The present invention achieves these and other objectives by providing, in one embodiment, a domestic refrigeration device which comprises an interior for storing foods, a light source arrangement which is configured to emit light, in particular white light, of different spectral characteristics into the interior, and a sensor unit which is configured to optically detect light emitted by the lit interior, to allocate to the detected light a value that is characteristic of the color of the emitted light, and to control the light source arrangement in such a manner that light of a specific spectral characteristic, which is dependent on the value that is characteristic of the color, is emitted. In the case of the described domestic refrigeration device, it is thus possible automatically to change a spectral characteristic of the illuminating light in dependence on the color of the displayed contents of the interior. In particular, it is possible, via the color, to draw conclusions about the possible contents of the interior. The dependence of the spectral characteristic of the illuminating light and the value that is characteristic of the color of the emitted light is typically specified beforehand.
The value that is characteristic of the color of the emitted light can be a value for the hue of the emitted light in the HSV color space. The value for the hue specifies the dominant wavelength of the color. Thus, the spectral characteristic of the illuminating light can be chosen and adjusted on the basis of the predominant color impression.
In particular, the light emitted by the light source arrangement can be white light with different correlated color temperatures. In the embodiment, the correlated color temperature (CTT) of the white light source is thus changed in dependence on the value that is characteristic of the color. The correlated color temperature describes the relative color temperature of a white light source. The grades of white range from cool white through neutral white to warm white. The color fields, or color locations, for the correlated color temperature lie on both sides of the radiation curve for black radiators of different temperatures (black-body curve) in the CIE color space. The white light can be achieved, for example, via a red, a yellow and a blue light source, in each case typically an LED. Alternatively, a blue/yellow light source, for example, can be used as the white light source, for example via an ultraviolet or blue radiating UV-LED which is coated with a yellow fluorescent phosphor. A red light source can also be added to the blue/yellow light source in order to enhance the warm component. The correlated color temperature of a light source arrangement can be achieved by changing the relative intensities of the different colored light sources.
The light source arrangement can be so configured that it emits light into a partial volume of the interior that is in the form of a separate storage region. In one embodiment, the separate storage region can be brought from a closed state into an open state and vice versa. The sensor unit can thereby further comprise a position sensor, in particular a Hall sensor or reed sensor, for detecting the closed state and the open state of the separate storage region. It can thus be determined, by means of the position sensor, whether the contents of the separate storage region may have changed and accordingly the lighting characteristic may have to be adapted to the new contents, that is to say whether the value that is characteristic of the color has to be determined. The contents of the separate storage region may have changed whenever the detection of a closed state takes place shortly after the detection of an open state of the separate storage region.
In one form of construction, the separate storage region can be a cold compartment, in particular for fresh foods, which is arranged to be displaceable between an open state and a closed state, wherein in the closed state of the cold compartment a base plate on which the light source arrangement and the sensor unit are provided is arranged above an open side of the cold compartment and spaced apart from the open side of the cold compartment. The base plate can serve as a shelf for foods, so that in this solution the light source arrangement and the sensor unit are integrated into existing components of the domestic refrigeration device.
In order to ensure that the cold compartment is lit as evenly and as reliably as possible, the light source arrangement can be arranged along a longitudinal direction of the base plate narrow side and inclined relative to the base plate narrow side in the direction towards the separate storage compartment. The base plate narrow side is, in particular, an end face of the base plate. The sensor unit can be arranged on a base plate flat side facing the cold compartment.
If the base plate has a screen into which the light source arrangement is integrated, and to which the sensor unit can also be fixed, the screen can advantageously be removably fixed to the base plate. The base plate is accordingly easy to clean.
In order to ensure good lighting of the cold compartment and at the same time protection for the light source arrangement, the screen can have a curved reflector portion opposite the light source arrangement. The reflector portion reflects, or scatters, the light emitted by the light source arrangement in the direction towards the cold compartment and protects the light source arrangement from external mechanical influences.
In one embodiment, the light source arrangement has a plurality of light sources, in particular light-emitting diodes, LEDs, which emit light of different wavelengths, and the sensor arrangement has a light sensor which is sensitive in the different wavelengths. In order to achieve maximum color sensitivity, the LEDs, or light sources, are activated in such a manner that they emit light temporally in succession. In particular, the light-emitting diodes are so matched to one another that they emit a white light.
In another embodiment, the sensor unit has a micro-camera for optically detecting the lit interior. Here too, the light source arrangement can be any desired light source, in particular white light source.
There is further provided a method of controlling a light source arrangement, wherein the light source arrangement is arranged in a domestic refrigeration device, in particular in a domestic refrigeration device as described above, which comprises an interior for storing foods, and the light source arrangement is configured to emit light, in particular white light, of different spectral characteristics into the interior. The method comprises the step of lighting the interior by means of the light source arrangement with light, in particular white light, optically detecting the light emitted by the lit interior, determining a value that is characteristic of the color of the emitted light, and controlling the light source arrangement in such a manner that light of a specific spectral characteristic, which is dependent on the value that is characteristic of the color, is emitted.
The value that is characteristic of the color of the emitted light can again be a value for the hue of the emitted light in the HSV color space. In order then to control the light source arrangement in such a manner that light of a specific spectral characteristic is emitted, in dependence on the value for the hue of the emitted light, the method can comprise the following steps: allocating the determined value for the hue to one of a plurality of color value groups, wherein a color value group in each case comprises one or more color value ranges, each color value group having color value ranges which are different from one another, and wherein each color value group is in turn allocated to a specific correlated color temperature, and activating the light source arrangement in such a manner that light with a correlated color temperature that corresponds to the correlated color temperature allocated to the color value group to which the determined value for the hue was allocated is emitted. In this variant, the correlated color temperature of the emitted light is thus changed. In particular, in this variant, the different color value groups, which contain different color value ranges, are each allocated to a correlated color temperature. This allocation is specified beforehand. Accordingly, it is possible, for example, to light foods of different color impressions, such as vegetables and milk products, that is to say in which the color impression is dominated by a different color in each case, with light of the same correlated color temperature.
The invention will be explained in greater detail below with reference to the accompanying drawings.
It is assumed in the following that the cold compartment designated 10 in the figure is intended to be arranged in a refrigerator. The refrigerator, which is not shown, has an interior which serves as the cold chamber for the cold storage of foods. The interior is delimited at the sides by two side walls, at the back by a rear wall, at the bottom by a bottom wall and at the top by a top wall. At the front there is provided a pivotably arranged door for opening and closing the refrigerator. The cold compartment 10 forms a separate storage region of the interior.
It is further assumed that the cold compartment 10 is displaceably arranged on the bottom wall of the refrigerator. Above the cold compartment 10 there is arranged a base plate 12, which can form a shelf for foods. The base plate 12 is typically displaceably fixed in a groove extending in the depth direction in the refrigerator and formed by in each case two adjacent projections provided on a side wall. The base plate 12 has two base flat sides 14, the upper side face, which serves as a shelf for foods, and the lower side face facing the cold compartment. At the periphery, the base plate has four narrow sides 16.
The cold compartment 10 is in the form of a drawer having a bottom wall 18, four side walls 20 and an open side 22 opposite the bottom wall 18. The front side wall 20 facing the user of the refrigerator has a handle 24 for utilising the cold compartment 10. The base plate 12 is arranged in the refrigerator above the cold compartment 10 and spaced apart from the open side 22 of the cold compartment 10, so that the cold compartment 10 can be moved without moving the base plate 12. The distance of the base plate 12 from the open side 22 of the cold compartment 10, or from the upper edges of the four side walls 20 of the cold compartment 10, is small and is typically not more than 1 cm, more preferably less than 1 cm.
As can be seen in the enlarged view of the front region of the base plate 12 of
In the embodiment shown in
The screen 30 also extends over a portion of the lower base plate flat side 14, namely over a front region, adjoining the base plate narrow side 16, of the lower base plate flat side 14. A sensor unit 36 is arranged in this region 34 of the screen 30 parallel to the base plate flat side 14. The sensor unit 36 is so configured and arranged that it can optically detect the interior of the cold compartment 10 lit by the light source arrangement 26, evaluate it and, in dependence on the result of the evaluation, activate the light source arrangement 26 in such a manner that light of a specific spectral characteristic, dependent on the result of the evaluation, is emitted. Further details are given hereinbelow.
In the sectional view shown in
The position sensor 38 can be, for example, a Hall sensor or a reed sensor. In order to be able to determine the relative position of the cold compartment 10, the cold compartment 10 is in one embodiment provided with a permanent magnet 40, the magnetic field of which cooperates with the position sensor 38. The permanent magnet 40 can be mounted, as is shown in
According to an embodiment shown in
In
The further embodiment shown in
Then, in step S140, the color defined by the three color values in the RGB color space is converted into the HSV color space. In particular, a value for the hue is determined. How such a conversion is to be carried out is known and is described by way of example hereinbelow.
Thereafter, in step S150, the determined color value for the hue is allocated to one of a plurality of color value groups. A color value group comprises one or more color value ranges, each color value group having color value ranges which are different from one another. The determined color value is allocated to the color group which has a color value range which comprises the determined color value. Each color value group is in turn allocated to a particular correlated color temperature.
In the embodiment shown, there are three color value groups. If the determined color value is allocated in step S150 to the first group (“Group 1”), the light source arrangement is activated in step S160 in such a manner that it emits light with a correlated color temperature of 3000 K. If the determined color value is allocated in step S150 to the second group (“Group 2”), the light source arrangement is activated in step S170 in such a manner that it emits light with a correlated color temperature of 2500 K. Finally, if the determined color value is not allocated in step S150 to either the first or the second group, it is allocated to a third group to which a correlated color temperature of 4000 K is allocated, and the light source arrangement is activated accordingly in step S180.
If the light source arrangement is provided by LEDs which emit light of different wavelengths, the color temperature, that is to say the color impression to the human eye, is determined inter alia by the relative intensities of the differently colored light. By changing the relative intensities, the color temperature of the light emitted by the LEDs can thus be changed.
This is illustrated again by means of
If, on the other hand, it is determined in step S120 that the state of the separate storage region does not change from an open state to the closed state, the light source arrangement continues to emit unchanged in step S190, that is to say it emits light with the same spectral characteristic, that is to say the same correlated color temperature, as previously. Alternatively, the light source arrangement can be activated in such a manner that the correlated color temperature is 4000 K.
An example of three color value groups with different color value ranges is mentioned as an example in the following. The first color value group comprises color values, that is to say values for the hue in the HSV color space, which lie in the range from 18° inclusive to 157.5° inclusive (green-yellow) and in the range from 279° inclusive to 324° inclusive. The second color value group comprises color values which lie in the range from 0° to 18° (red) and in the range from 342° inclusive to 360° (red). Finally, the third color value group comprises all the color values that are not included in the first and second color value groups, as well as the color value 0. The correlated color temperature allocated to the first color value group is, as described in relation to
In order that the color value can reliably be used according to the above-described method to specify the correlated color temperature of the light source, the color rendering index (CRI) of the light source should be at least 90. The color rendering index is a characteristic number which describes the quality of the color rendering of light sources of the same correlated color temperature.
By means of the above-described method it is possible, for example, to light fish and seafood stored in the cold compartment with white light with a correlated color temperature of 4000 K, fruit and vegetables as well as cheese and other fresh dairy products with light with a correlated color temperature of 3000 K, and bread and baked goods with light with a correlated color temperature of 2500 K, without the object as such, that is to say the type of food, being determined directly, but only via the hue of the light emitted, that is to say reflected or scattered, by the lit foods. In particular, it is possible, according to the contents of the cold compartment, to set the “hue” for the illuminating light automatically, so that the foods appear as appealing as possible to the user. Consequently, it is possible to adapt the correlated color temperature of the illuminating light to the contents of the cold compartment without having to determine the contents themselves.
According to one embodiment, the conversion of the color defined by the three color values in the RGB color space into the HSV color space, or the determination of the hue value on the basis of the RGB color values, is carried out by the following formula:
HUE=60*(h+[φ/Max(R;G;B)−Min(R;G;B]). (1)
In the formula
The values for h and φ are determined according to which of the color values of the RGB color space is the greatest.
If Max(R;G;B) is the R value, then h=0.0 and φ=G−B.
If Max(R;G;B) is the G value, then h=2.0 and φ=B−R.
If Max(R;G;B) is the B value, then h=4.0 and φ=R−G.
If the hue value so calculated is less than 0, then that value huecalc is increased by 360, that is to say Hue (if HUEcalc.<0)=HUEcalc.+360.
Thus, by way of example, in the case where R=180, G=75 and B=113:
HUE=60*(0.0+[75−113)/180−75)]))=−21.7143, and since this calculated value is less than 0:
HUE=−21.7143+360=338.2857°.
Although the preferred embodiments of the present invention have been described herein, the above description is merely illustrative. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as defined by the appended claims.
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