DE102017012206B4 - Electrical household appliance with color temperature variable lighting device - Google Patents

Abstract

An electrical household appliance, in particular a refrigerator or a washing machine, comprises a device interior which can be closed by a door, a lighting device for illuminating the device interior and a control device for controlling the lighting device. In certain embodiments, the control device is designed to operate the lighting device in a first lighting mode depending on the detection of a state of relatively lower loading of the device interior and to operate the lighting device in a second lighting mode depending on the detection of a state of relatively larger loading of the device interior to effect, wherein in the first lighting mode, the light emitted by the lighting device into the interior of the device has a higher proportion of blue than in the second lighting mode.

Description

The invention relates to an electrical household appliance with a lighting device for illuminating an interior of the household appliance.

It is common practice to make it more convenient for a user to load and unload the interior of an electrical household appliance with items that are to be kept cool in the interior or otherwise treated (e.g., cooked or washed) by illuminating the interior. In the case of an electric oven, the lighting of the interior also has the purpose of enabling the user to observe the food to be cooked through a viewing window provided in the oven door and thus to visually check the cooking progress during the cooking process. In conventional ovens, the viewing window is often made of such a material or has such a structure that radiation in the infrared wavelength range can only penetrate the viewing window in the direction from the cooking chamber to the outside comparatively poorly. This is to keep heat losses due to escaping infrared radiation low. The result of this filter function is that not only those radiation components that are invisible to the human eye, but also radiation components in the visible red area are blocked by the viewing pane against the passage to the outside. On the other hand, if the user opens the oven door, this filter function is no longer available, which is why the color impression of the illuminated interior can differ significantly for the user, depending on whether the door is open or closed. Because of the filter function of the viewing window explained, the user can perceive the interior light as warmer when the door is open because of the red component that is increasingly coming outwards than when the door is closed. Under the changed lighting conditions with the door open, the progress of the cooking process can be different for the user than when the door is closed when he looks at the food through the viewing window.

The invention provides an electrical household appliance as defined in the claims. The lighting device of the household appliance is designed to be operated in different lighting modes, which differ in the spectral composition of the light emitted by the lighting device into the interior of the device. The subjective color impression of an observer can be influenced by varying the spectral composition of the light. In certain embodiments, the lighting device is designed to be operated in a plurality of lighting modes that can be changed in discrete steps. In other embodiments, the lighting mode of the lighting device can be changed continuously.

In certain embodiments, at least in a partial number of the lighting modes, the light of the lighting device emitted into the interior of the device is a white light, the different spectral composition of the light in the different lighting modes being associated with a different color temperature of the white light.

In certain embodiments, the lighting device comprises a plurality of light sources which are designed to emit light of different spectral content, the lighting modes differing in a different operating combination of the light sources. The light sources can be, for example, light-emitting diodes (in short: light-emitting diodes or LEDs), the invention not being restricted to this technology of light sources. At least one of the light sources can be a white light source. For example, it is provided in certain embodiments that the light sources comprise at least two white light sources, which are designed to emit white light of different color temperatures. In other embodiments, it can be provided that the light sources comprise at least one red light source and / or at least one blue light source and / and at least one yellow light source. For example, in certain embodiments, a first light source designed as a blue or red light source is combined with a second light source designed as a white light source.

In certain embodiments, the operating combinations comprise at least two operating combinations, which differ by a different combination of radiation intensities of at least two of the light sources. Different combinations of radiation intensities can consist, for example, in that the radiation intensity with which a first of the light sources is operated is changed between a first operating combination and a second operating combination, while the radiation intensity with which a second of the light sources is operated with the first and the second operating combination is the same in each case. However, it is possible that the radiation intensity of this second light source is also varied between the first operating combination and the second operating combination. To influence the radiation intensity, for example, an electrical quantity with which the light source in question is controlled, for example a drive voltage or a drive current, can be varied with regard to the magnitude.

In certain embodiments, the operating combinations include a first operating combination in which a particular one of the light sources is turned off and at least a second operating combination in which the particular light source is turned on. By switching a light source on and off while another light source is operated with a constant (or possibly varying) radiation intensity, it is also possible to modify the spectral composition of the light emitted by the lighting device into the interior of the device.

In order to obtain a mixture of the light from the light sources in the interior of the device (the mixing result depending on the lighting mode being different with regard to the spectral content), in certain embodiments the lighting device according to the invention comprises a reflective and / or transmissive scattering structure for mixing the light from each of the light sources. For example, the lighting device in the beam path between the light sources and the interior of the device can have a reflection surface, from which light incident thereon is directed in the direction of a transmissive light exit disk, through which the light enters the interior of the device. In order to realize a reflective scattering structure, in such a configuration of the lighting device, the reflection surface can be designed with a sufficiently strong surface roughness, at least in partial areas, so that light that falls on the relevant partial areas is not reflected in a directional manner, but diffusely scattered. As an alternative or in addition, the light exit pane can cause diffuse light scattering, for example by making the light exit pane milky or / and by means of etching processing, laser engraving or other processing technology, scattering zones are formed on a pane surface or within the pane material of the light exit pane.

In certain embodiments, the lighting device comprises a transmissive light exit structure common to each of the plurality of light sources, from which the light of the lighting device exits into the equipment room. The light exit disk mentioned can form such a common transmissive light exit structure.

In certain embodiments, the lighting device comprises an evaluation unit which is set up to determine a first control variable representative of the duty cycle of the control signal from a pulse-width-modulated control signal and to assign a first light source (or a group of first light sources) from the plurality of light sources depending on the first control variable Taxes. Control information can thus be provided via the duty cycle of the control signal (ratio of pulse width to period duration), which enables the evaluation unit to control the operation of at least one of the light sources. By continuously changing the duty cycle of the control signal, it is in particular possible to continuously vary a control variable derived from the duty cycle, for example an electrical control voltage.

Control information can also lie in the period of a periodic but frequency-variable control signal. In certain embodiments, this is used to transmit two control information for two different light sources or two groups of different light sources via a pulse-width-modulated control signal. A first piece of control information lies in the duty cycle of the control signal, a second piece of control information in the period of the control signal. Accordingly, in these embodiments, the evaluation unit is set up to determine a second control variable representative of the period of the control signal from the pulse-width-modulated control signal and to control a second light source (or a group of second light sources) from the plurality of light sources depending on the second control variable.

The household appliance is, for example, a refrigerator.

In one embodiment of the household appliance as a cooling device, in which the interior of the device forms a cooling room, the cooling device can comprise a control device which is designed to operate the lighting device in a first lighting mode depending on the detection of a state of relatively low loading of the cooling room and depending on the detection of a state of relatively greater loading of the cooling space to cause the lighting device to operate in a second lighting mode, the light emitted by the lighting device into the cooling space having a higher blue component in the first lighting mode than in the second lighting mode. For presentation purposes in business premises, a colder color temperature of the interior lighting of the refrigerator is occasionally sought, since the device can then appear more aesthetically pleasing to a potential buyer. In the case of domestic use, on the other hand, an incentive to buy is not important; here it has been shown that a warmer color temperature of the refrigerator compartment lighting is often perceived by the user as more pleasant. In showrooms of a retail store, the cooling device is typically presented to the public empty; on the other hand, it is regularly more or less heavily loaded in domestic operation. By detection of the load condition of the cold room, for example by means of a camera and subsequent Image evaluation, the control device of the cooling device can therefore differentiate whether the cooling device is in domestic use or not. Depending on the result of this detection, the control device can set a higher or lower proportion of blue in the light emitted by the lighting device into the cooling space and thus a different color temperature of this light.

According to a further embodiment, the household appliance can comprise a control device which is designed to operate the lighting device in a different lighting mode at different times of the day. This is based on the knowledge that the human eye can have a different color perception at different times of the day, for example depending on the brightness of the ambient light and / or the spectral composition of the ambient light. may vary depending on whether the ambient light is natural light or comes from an artificial light source. Fatigue of the eye can also lead to a change in the color perception. The human eye is typically rested in the morning after getting up and can therefore give a different color impression than later in the day when the eye may already be tired. The household appliance can include suitable means, for example for detecting the time of day or / and the brightness of the ambient light or / and the spectral composition of the ambient light and, depending on the information acquired in this way, setting a suitable lighting mode of the lighting device.

• 1 schematisch Komponenten eines Haushalts-Backofens gemäß einem Ausfü h ru ngsbeispiel,
• 2 schematisch Komponenten einer beispielhaften Leuchtvorrichtung zur Innenraumbeleuchtung eines elektrischen Haushaltsgeräts,
• 3 schematisch eine Leiterplatte mit einer Mehrzahl Leuchtquellengruppen,
• 4 einen beispielhaften zeitlichen Verlauf eines pulsweitmodulierten Steuersignals als Träger zweier Steuerinformationen,
• 5 schematisch Komponenten eines Haushalts-Kühlgeräts gemäß einem Ausführungsbeispiel, und
• 6 schematisch Komponenten einer Haushalts-Waschmaschine gemäß einem Ausführungsbeispiel.

The invention is explained below with reference to the accompanying drawings. They represent:

• 1 schematically components of a household baking oven according to an exemplary embodiment,
• 2 schematically components of an exemplary lighting device for interior lighting of an electrical household appliance,
• 3 schematically a circuit board with a plurality of light source groups,
• 4 an exemplary temporal course of a pulse-width modulated control signal as a carrier of two control information,
• 5 schematically components of a household refrigerator according to an embodiment, and
• 6 schematically components of a household washing machine according to an embodiment.

It will start on 1 directed. The household oven shown there is generally designated 10. It includes a cooking space 12 forming oven muffle 14 as well as a pivoting oven door 16 to close the cooking space 12 , In the oven door 16 is a viewing window 18 formed, the window pane is transparent and to reduce heat loss during cooking of the oven 10 has a filter function for infrared radiation, through which such radiation exits the cooking space 12 through the window 18 is hindered. In at least one of the cooking space 12 bounding muffle walls of the furnace muffle 14 is a light module designed as a surface light 20 built-in. In the example shown, there are two opposite side walls 22 the oven muffle 14 at least one such light module each 20 built-in. The light module 20 is a prefabricated unit, which as such in a suitable wall opening in the relevant muffle wall of the furnace muffle 14 can be used and a (not shown in the drawings) module housing with a receptacle for a connector 23 one of the electrical supply and control of the light module 20 serving connecting cable 24 having. The connection cable 24 connects the light module 20 with an electrical control module 26 the oven 10 , In addition to controlling the light module 20 is the control module 26 for controlling any other operating functions of the oven 10 responsible.

A door sensor 28 is used to detect the position of the oven door 16 , Based on the detection signal from the door sensor 28 can the control module 26 determine if the oven door 16 is closed or whether it is (at least partially) open. According to a functionality not according to the invention, the control module controls 26 depending on whether the control assembly 26 a closed state or an open state of the furnace door 16 detects the light module 20 different in lighting mode. Specifically, the control module controls 26 the light module 20 in lighting mode with the oven door closed 16 so that the light module 20 works in a first lighting mode in which that of the lighting module 20 in the cooking space 12 emitted light has a relatively stronger red component than in a second lighting mode, to which the control module 26 the light module 20 controls when the control module 26 an open position of the oven door during lighting operation 16 detected. The increased proportion of red in the first lighting mode compared to the second lighting mode makes the filtering effect of the viewing window of the viewing window 18 for infrared radiation (this filter effect typically extends into the visible red area) at least partially, so that the user has an at least similar or even the same color impression when he is open oven door 16 in the cooking space 12 looks and the other time with the oven door closed 16 through the window 18 through into the cooking space 12 looks.

The light module can be used to implement the different light modes 20 comprise a plurality of individually controllable light-emitting diodes, each with a different spectral content of the light emitted by the light-emitting diode in question. In this regard, is now supplementary 2 referenced, the schematic representation of an exemplary embodiment of the light module 20 shows. The light module 20 has a circuit board in this embodiment 30 on which at least one group is expediently mounted closely adjacent to each other. In the example shown, the group comprises a total of two light-emitting diodes 32 ₁ . 32 ₂ ; it goes without saying that the group can also contain more than two light-emitting diodes, for example three. Each of the LEDs 32 ₁ . 32 ₂ The group is designed for a different spectral composition of the emitted light from the relevant light-emitting diode. For example, one of the LEDs 32 ₁ . 32 ₂ one white light LED with a lower color temperature, while the other of the light emitting diodes 32 ₁ . 32 ₂ is a white light LED with a higher color temperature. For example, a color temperature in a range between approximately 2000 and 3000 K can be selected for the colder white light LED and a color temperature in a range between approximately 5000 and 6000 K can be selected for the warmer white light LED. Other color temperature values are of course conceivable. According to another example, one of the light emitting diodes 32 ₁ . 32 ₂ a white light LED, in particular a white light LED with a comparatively low color temperature, while the other of the light emitting diodes 32 ₁ . 32 ₂ is a red light LED. Depending on the dimensions of the light module 20 can on the circuit board 30 if necessary, several LED groups can be installed, as exemplified in 3 is indicated. In the case of several LED groups, each group preferably contains the same combination of LEDs. In the example shown, each of the LED groups consists of one LED 32 ₁ and a light emitting diode 32 ₂ ,

The light module 20 includes in the embodiment according to 2 also a reflection body 34 which has a reflective surface 36 forms, as well as a light exit disc made of translucent material 38 which according to the installation situation 1 approximately flush with the muffle wall in question 14 lies in which the light module 20 is installed. At least a large part of that from the LEDs 32 ₁ . 32 ₂ radiated light first hits the reflection surface 36 which the light towards the light exit disc 38 directs. For the purpose of mixing the light of the two light-emitting diodes as homogeneously as possible 32 ₁ . 32 ₂ is the light exit disc 38 designed as a diffuser. As an alternative or in addition, the reflection surface 36 have a diffuse scattering effect, for example by providing a sufficiently large surface roughness at least in some areas of the reflection surface 36 , The aim is for the light of the light emitting diodes 32 ₁ . 32 ₂ if it is the light emission disc 38 leaves, is sufficiently mixed so that the user does not perceive the individual light of a light-emitting diode, but only perceives a total light that results from the mixing of the light from both light-emitting diodes 32 ₁ . 32 ₂ results.

Basically, it is conceivable that the control module 26 separate control signals for the LEDs 32 ₁ . 32 ₂ each LED group via the connection cable 24 to the light module 20 supplies. Instead of separate control signals, the control module generates 26 on the other hand, in an embodiment explained in more detail below, a common control signal which carries two different control information items, namely control information for the light-emitting diode 32 ₁ and control information for the light emitting diode 32 ₂ , In the specific example, this common control signal is a pulse-width-modulated signal with a variable duty cycle and variable period. 4 shows an exemplary time course of such a pulse-width-modulated control signal (named with s (t)). It can be seen that the control signal s (t) (the variable t stands for time) during a first phase pulses of a period of time T _s1 which follow each other with a frequency 1 / T _P1 ( T _P1 is the period of the pulses of the control signal s (t)). The duty cycle of the control signal s (t) is the ratio of the pulse width to the period (ie T _s1 / T _P1 ) and is approximately 50% in the first phase mentioned, as can be seen in 4 can easily be extracted by simply comparing sizes. In a later second phase of the control signal s (t), the period has a value T _P2 shortened, ie the pulse rate has increased to 1 / T _P2 . The pulse width has reached a value in this second phase T _s2 reduced what is shown in the graphic representation of the 4 about a third of the period T _P2 equivalent. The duty cycle T _s2 / T _P2 is thus approximately 33% in the second phase.

The light module 20 has a suitable evaluation unit, which in 2 at 40 is indicated, together with the LED groups on the circuit board 30 can be mounted and evaluates the received control signal s (t) with regard to the duty cycle and the pulse frequency (period). The evaluation unit generates on the basis of the determined duty cycle 40 a first control variable, with which it is one of the two LEDs 32 ₁ . 32 ₂ controls each LED group. Based The evaluation unit generates on the determined pulse frequency (period duration) 40 a second control variable with which it is the other of the light emitting diodes 32 ₁ . 32 ₂ controls. The first and the second control variable are each a control current, for example, which is applied to the relevant light-emitting diode 32 ₁ . 32 ₂ is applied and determines the radiation intensity of the relevant light-emitting diode. The control module 26 and the evaluation unit 40 can cooperate in such a way that both LEDs 32 ₁ . 32 ₂ each LED group can be operated in a continuously variable manner via the pulse duty factor or the pulse frequency of the control signal s (t), or at least one of the LEDs 32 ₁ . 32 ₂ is operated changeable in discrete steps. In a simple case, the discrete steps can mean an on / off operation of the relevant light-emitting diode, ie the light-emitting diode is either switched off or it is operated with a constant radiation intensity. The discrete steps can alternatively comprise several switch-on states of different radiation intensity of the relevant light-emitting diode.

With the explained technique of driving the LEDs 32 ₁ . 32 ₂ Different spectral compositions of the total of the light module can be controlled via the control signal s (t) 20 emitted mixed light can be realized. In the case of using the light module 20 in the oven 10 the 1 for example, an embodiment is possible in which one of the light-emitting diodes 32 ₁ . 32 ₂ is a white light LED that is always operated with constant radiation intensity and the other light emitting diode is one with the oven door closed 16 switched on and with the oven door open 16 the red light LED is off. In another embodiment, both LEDs are 32 ₁ . 32 ₂ designed as white light LEDs, but with different color temperatures, with the oven door closed 16 the warmer of the two white light LEDs is operated with a relatively stronger radiation intensity compared to the colder one of the white light LEDs than when the furnace door is open 16 ,

For the purpose of briefly explaining two other possible areas of application for the light module 20 is now on the 5 and 6 directed. The same or equivalent components are provided with the same reference numerals, but supplemented by a lower case letter. Unless otherwise stated below, reference is made to the explanations above for the explanation of such components 1 to 4 directed.

In 5 is a generally designated 42a household refrigerator with a cabinet body 44a and a closet door 46a shown. The interior of the cabinet body 44a forms a cold room 48a , which is used for the cool storage of food. For reasons of clarity, shelves, drawers and other storage aids that are usually found in a refrigerator are in 5 not shown.

A light module 20a is in one of the cold room 48a bounding body walls of the cabinet body 44a built-in to with the refrigerator door open 46a the refrigerator 48a illuminate. Depending on the load condition of the cold room 48a becomes the light module 20a from a control module 26a set in different light modes. Specifically, the control module 26a in the case of detection of an empty or slightly filled condition of the cold room 48a such a control of the light module 20a that that's from the light module 20a in the cold room 48a emitted light has a stronger blue component than in a case in which the refrigerator is loaded more 48a with food is determined. To determine the load status, the refrigerator includes 42a a schematically indicated camera 50a which send their camera data to the control module 46a delivers the information from the camera images by means of suitable image evaluation software about the loading condition of the cold store 48a generated. To vary the blue component of the light module 20a emitted light can be one of the light emitting diodes 32 ₁ . 32 ₂ each LED group can be, for example, a blue light LED and the other LED can be formed by a white light LED. Depending on the detected loading condition, the blue light LED can be switched on or off, for example, while the white light LED is operated with constant beam intensity. Alternatively, both LEDs can be used 32 ₁ . 32 ₂ be formed by white light LEDs each with a different color temperature, the ratio of the radiation intensities of the two light-emitting diodes being varied as a function of the detected loading state.

In 6 is a household washing machine 52b shown one in a machine frame 54b rotating wash container 56b includes. Through an access hatch (not shown) in the machine frame 54b is the wash tank 56b accessible. The access hatch can be closed in the usual way by a door (also not shown in detail). A light module 20b serves to illuminate the interior of the washing container 56b in which the laundry to be washed is filled. The light module 20b can for example be inserted in a door seal, not shown, which extends around the access hatch and the door mentioned relative to the machine frame 54b seals. A camera 50b is used to take color pictures of the interior of the washing container 56b , The one from the camera 50b Color images are supplied by a control module 26b with the aim of a color analysis of in the washing container 56b filled laundry evaluated. There is predominantly white laundry in the washing container 56b controls the control module 26b the light module according to a functionality not according to the invention 20b in a lighting mode, in which that of the lighting module 20b Light emitted into the interior of the container has a stronger blue component than in another lighting mode in which the control module 26b the light module 20b sets when the presence of colored laundry in the washing tub 56b is detected.

Claims (2)

Electrical household appliance (42a) with a device interior (48a) closable by a door (46a), a lighting device (20a) for illuminating the device interior and a control device (26a) for controlling the lighting device, characterized in that the control device (26a) is designed for this purpose depending on the detection of a state of relatively lower loading of the device interior (48a), the lighting device (20a) is to be operated in a first lighting mode and, depending on the detection of a state of relatively larger loading of the device interior (48a), the lighting device (20a ) in a second lighting mode, wherein in the first lighting mode the light emitted by the lighting device (20a) into the interior of the device (48a) has a higher proportion of blue than in the second lighting mode. Electrical household appliance (42a) according to the preamble of Claim 1 , characterized in that the control device (26a) is designed to operate the lighting device (20a) in a different lighting mode at different times of the day.

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