DE29914037U1 - Indoor lighting for household appliances - Google Patents

Description

AGm 22 DE

Cu/sp

AKO-Werke GmbH & Co. KG, 88239 Wangen Interior lighting for household appliances

The innovation concerns interior lighting for household appliances, preferably refrigerators and freezers as well as washing machines and tumble dryers, which is switched on by opening a door or by operating a manual switch.
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According to the current state of the art, incandescent or halogen bulbs are used as light sources for such interior lighting. These have a relatively high power consumption (5 to 25 watts) and a high power loss. They emit around 95 to 97% of the power consumed as heat and only the rest in the form of light. This heat emission means an additional, unwanted supply of heat to the refrigerator compartment, particularly in refrigerators and freezers, which must be processed by the cooling unit. In addition, the service life of these lamps is quite short at less than 1,000 hours, also due to the frequent switching on. The lamps must therefore be replaceable in the event of a defect, and the required contact protection must be guaranteed. In addition, explosion protection when using potentially explosive coolants is only given with encapsulated bulb sockets, contacts and switches.

Based on this state of the art, the innovation is based on the task of creating interior lighting for household appliances which does not have the aforementioned disadvantages and nevertheless offers sufficient illumination of the interior of the household appliance.

This object is achieved by an interior lighting for household appliances with the features of claim 1. Embodiments and further developments of the innovation are described in the subclaims.

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Until now, light-emitting diodes could not be used to illuminate the interior of a household appliance because, on the one hand, they did not shine brightly enough and, above all, because semiconductor diodes that emitted blue light were not available, which made it possible to generate white light by superimposing it with other colors.

The use of LEDs as light sources for the interior lighting of household appliances avoids the disadvantages mentioned above. LEDs have a very low power consumption (0.01 to 0.1 watts), which is why energy consumption is significantly reduced compared to conventional light bulbs, even when several or numerous LEDs are used. The better efficiency of the LED (approx. 20% compared to 5% for the light bulb) means that heat is emitted significantly less through power loss, which practically completely prevents unnecessary and, in the case of refrigerators and freezers, undesirable heating of the illuminated interior of the household appliance. In addition, LEDs have a very long service life of 100,000 hours, which is why they do not need to be replaced during the life cycle of a household appliance and the customer service effort required for this is eliminated.

To achieve the luminosity of a light bulb, several light-emitting diodes are required, which are at least partially connected in parallel and/or in series. The lighting is switched on and off using an electronic switch, preferably a transistor. This makes it possible to achieve simple explosion protection for refrigerators and freezers and to use a single-wall evaporator in the cooling circuit even when using potentially explosive coolants.

The interior lighting can be in different colors, but white light is preferably used. In one embodiment, luminescence conversion diodes that emit white light are used for this purpose. In these, part of the blue light generated by a semiconductor diode is converted into yellow light, with white light being generated by the superposition of these two colors. In another embodiment, light-emitting diodes are used that have semiconductor diodes that generate light in different colors.

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sen, whereby white light is created by the superposition of the different colors (preferably yellow and blue or red, green and blue).

In a further development, the light-emitting diodes are distributed over at least part of the interior of the household appliance, resulting in uniform illumination of this interior.

One embodiment of the innovation as refrigerator lighting will be explained in more detail below using the following illustrations. They show:

Figure 1 an opened refrigerator with interior lighting and
Figure 2 shows a circuit arrangement for the LEDs of the interior lighting.

According to the innovation, a refrigerator 1 has a large number of luminescence conversion LEDs 5 emitting white light on the inner surfaces of its side walls 2, rear wall 3 and ceiling 4. The LEDs are evenly distributed over the inner surfaces of the refrigerator 1, resulting in very even illumination of the refrigerator interior. The door 6 of the refrigerator 1 closes with the help of magnetic contacts 7 and 8.

Instead of using individual LEDs 5, several LEDs 5 can be combined to form LED groups and several such LED groups can be distributed over the inner surfaces of the refrigerator.

As can be seen in Figure 2, a Zener diode 9 is connected in parallel and in reverse direction to each LED 5. This serves to bridge the respective LED 5 should it fail.

Three light-emitting diodes 5 are connected in series with a series resistor R to form a light-emitting diode branch 10. Several such light-emitting diode branches 10, not all of which are shown in Figure 2, are connected in parallel with one another, with their positive pole connected to the positive operating voltage Ub and their negative pole connected to earth via a transistor 11.

This connection of the LEDs in Fig. 2 is only shown as an example. Within the scope of the innovation, numerous different connections are possible, such as the series connection of more or less than three LEDs 5 to form a LED branch 10 or the parallel connection of one Zener diode 9 with several LEDs 5, which in turn can be connected to one another in parallel or in series.

When the door 6 of the refrigerator 1 is opened, the magnetic contacts 7 and 8 are separated, whereby a switching voltage + Us is applied to the base of the transistor 11 via resistor R'. This turns on the transistor 11 and switches on the interior lighting.

If one of the LEDs 5 fails, the corresponding Zener diode 9 breaks down due to the high voltage now applied to it, whereby the failed LED is bypassed and the remaining LEDs 5 of the corresponding LED branch can still operate. Thus, even if one or more LEDs 5 fail, the interior lighting continues to function with only a slightly lower brightness.

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Claims (5)

1. Interior lighting for household appliances, preferably refrigerators and freezers as well as washing machines and tumble dryers, which is switched on by opening a door or by operating a manual switch, characterized in that one or more light-emitting diodes ( 5 ) (LEDs) are provided as lighting means, which are connected to one another in parallel and/or in series and can be switched by means of a preferably electronic switch, preferably a transistor ( 11 ). 2. Interior lighting according to claim 1, characterized in that luminescence conversion diodes emitting white light are used as lighting means. 3. Interior lighting according to claim 1, characterized in that several light-emitting diodes emitting different colors, preferably yellow and blue or red, green and blue light, are used as the lighting means, whereby white light is produced by the superposition of the different colors of the individual light-emitting diodes. 4. Interior lighting according to one of claims 1 to 3, characterized in that a Zener diode ( 9 ) is connected in parallel in the blocking direction to each light-emitting diode ( 5 ) or group of light-emitting diodes ( 5 ). 5. Interior lighting according to one of the preceding claims, characterized in that the light-emitting diodes ( 5 ) are distributed over the interior or part of the interior of the household appliance ( 1 ), thus resulting in uniform illumination of the interior.