The present invention relates to a washing machine with a wash drum lighting device.

As is known, last-generation household washing machines are equipped with a lighting device, normally located inside the wash chamber of the machine to illuminate the drum, so that the laundry inside the drum is visible to the user during and/or at the end of the wash cycle. An example is disclosed in EP 1048775.

More specifically, the lighting device comprises a halogen or incandescent lamp located inside the wash chamber, at the door opening of the machine, and oriented to light the inside of the drum; and an electric control circuit for supplying the lamp with a given electric power.

The washing machine lighting device described above has various drawbacks.

Firstly, in addition to requiring a large amount of electric power, with obvious drawbacks in terms of consumption, the incandescent or halogen lamps of lighting devices of the above type also have the major drawback of high operating temperature. As a result, to keep the lamp at a stable temperature below a given danger threshold, highly complex electronic control circuits are required to control power supply to the lamp as a function of the temperature of the lamp, and so prevent overheating and the risk of fire.

Secondly, halogen or incandescent lamps indiscriminately illuminate all the space surrounding the lamp, as opposed to producing a light beam directed solely onto the drum area to be illuminated. In point of fact, a large percentage of the light beam emitted by the lamps of currently used lighting devices is wasted.

Finally, the working life of lamps of lighting devices of the above type is seriously affected by the degree of machine vibration and the number of switching operations of the electric control circuit. As a result, the lamp is frequently damaged when subjected to severe vibration or when a given switching threshold is reached.

It is an object of the present invention to provide a washing machine comprising a wash drum lighting device designed to eliminate the drawbacks of known lighting devices.

According to the present invention, there is provided a washing machine comprising a wash drum lighting device as claimed in the accompanying Claims.

A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

• Figure 1 shows, schematically, a washing machine comprising a wash drum lighting device and in accordance with the teachings of the present invention;
• Figure 2 shows a schematic detail of the Figure 1 lighting device;
• Figure 3 shows a block diagram of the electronic control unit of the Figure 1 lighting device.

Number 1 in Figure 1 indicates as a whole a household washing machine substantially comprising a substantially parallelepiped-shaped outer casing 2, one outer face of which has an opening 3 to which a door (not shown) is hinged.

Washing machine 1 also comprises a wash chamber 5 housed inside casing 2 and connected to opening 3 by a tubular seal or bellows 6; and a wash drum 7 housed inside wash chamber 5 and rotated, in use, by a drive unit (not shown) about a substantially horizontal axis of rotation A.

Washing machine 1 also comprises a lighting device 8 for lighting wash drum 7 and which, unlike the wash drum lighting devices of known washing machines, comprises one or more LEDs 9 for emitting one or more light beams towards the opening of wash drum 7 to illuminate the inside of the drum.

In the Figure 1 and 2 example, lighting device 8 comprises a substantially ogival casing or shell 10, which has a lens 11 at one end 10a and fits stably, but in easily removable manner, inside a seat 12 formed in bellows 6, so that lens 11 faces wash drum 7 (Figure 1).

Lighting device 8 also comprises a supporting rod 13, which has LED 9 at one end 13a and fits axially inside a tubular cavity 14 formed in shell 10, so that LED 9 is positioned facing lens 11 of shell 10. Lens 11 provides for concentrating the light beam from LED 9 onto wash drum 7, and, in the example shown, is designed to produce a light-emitting cone with an angle α of about 80°.

In an alternative embodiment employing a number of LEDs 9, lens 11 provides for appropriately collimating the light beams from LEDs 9 onto wash drum 7.

In the Figure 2 example, shell 10 is made of preferably transparent plastic material, and, in addition to the optical function described above, also protects LED 9 on rod 13 against water.

More specifically, shell 10 is provided on the end with a number of axially spaced lock seals 15, which, on the one hand, seal the end of seat 12 facing wash drum 7, to protect LED 9 against water, and, on the other, assist in locking shell 10 axially inside seat 12.

Shell 10 also has two longitudinal anchoring flanges 16, which project from the opposite end of shell 10 to lens 11, are positioned facing and parallel to each other, and the free end of each of which has a supporting edge 16a which, when shell 10 is fitted inside seat 12, rests on the end edge of seat 12 opposite wash drum 7 to prevent axial movement of shell 10 towards wash drum 7.

Supporting rod 13 is substantially cylindrical, is made of metal, such as aluminium or any other similar metal material, and provides for dissipating into the outside atmosphere the heat generated by LED 9.

The body of rod 13 has two longitudinal grooves 17 (only one shown in Figure 2), each for housing a portion of conducting wire of LED 9; and two anchoring tabs 18 (only one shown in Figure 2) which fit inside respective seats (not shown), formed in the inner walls of tubular cavity 14 of shell 10, to mechanically connect rod 13 and shell 10 into one body.

Seat 12 is substantially complementary in shape to the outer shape of shell 10, and is preferably integrated in the top portion of bellows 6 to reduce exposure of lighting device 8 to water.

In the Figure 2 example, seat 12 extends along an axis B preferably lying in a vertical diametrical plane of bellows 6 and substantially sloping with respect to horizontal axis A of the wash drum.

In an alternative embodiment, axis B is substantially parallel to axis A, and seat 12 extends substantially on the inner wall of bellows 6.

With reference to Figure 3, lighting device 8 also comprises an electronic control unit 19 connected to and for supplying electric operating power to LED 9.

Electronic control unit 19 substantially comprises a power block 20 for generating the current/voltage supply of LED 9; a detecting block 21 for detecting the junction temperature T_G of LED 9; and a control block 22 for controlling power block 20 as a function of the temperature T_G reading.

More specifically, power block 20 may be defined by an electronic PWM (Pulse Width Modulation) circuit connected to the two input terminals of LED 9 to supply electric power to the LED, and having an input supplied with a control signal S_COM indicating the electric power to be supplied to LED 9.

Detecting block 21 is input-connected to the two input terminals of LED 9, and has an output supplying a current/voltage signal S_T proportional to the junction temperature T_G of LED 9; and control block 22 receives and processes signal S_T to produce, as a function of the junction temperature T_G reading, signal S_COM coding the value of the electric power to be supplied to LED 9.

More specifically, control block 22 may be defined by a microprocessor, which compares the temperature T_G reading with a predetermined maximum temperature threshold T_S, and, in the event the temperature T_G reading exceeds the predetermined maximum temperature threshold T_S, provides for controlling power block 20 to reduce the electric power supply to LED 9 and so reduce the junction temperature of LED 9.

In other words, electronic control unit 19 acts as an electronic closed-loop circuit, which controls LED 9 to keep its junction temperature stable below the predetermined maximum temperature threshold T_S.

LED 9 of lighting device 8 may be defined by a one-colour LED to generate a light beam of one predetermined colour; or by a multicolour RGB diode for generating a number of light beams of different colours, i.e. a number of light beams of different frequency spectrums; or by a number of LEDs, each emitting a light beam of a different colour.

If lighting device 8 comprises a multicolour RGB diode or a number of LEDs of different colours, the colour of the light beam directed onto wash drum 7 can be varied as a function of the operating conditions and/or operating status of washing machine 1.

Electronic control unit 19 is able to control the multicolour RGB diode to generate a light beam with a frequency spectrum, i.e. a colour, associated with a given operating condition or a given operating status of the washing machine.

More specifically, electronic control unit 19 may control the multicolour RGB diode or the LEDs to generate a light beam of a predetermined first colour, e.g. red, when the operating status corresponds to the start of the wash cycle; and/or to generate a light beam of a predetermined second colour, e.g. green, when the operating status corresponds to the end of the wash cycle; and/or to generate a light beam of a predetermined third colour, e.g. yellow, when washing machine 1 is in an intermediate wash cycle status.

Emission of different-coloured light beams may be activated by control block 22 on the basis of an information signal S_INF supplied to control block 22 by an additional external control module for controlling and monitoring the operating status of washing machine 1.

Lighting device 8 of washing machine 1 described above has numerous advantages.

Firstly, using LED 9 provides for : reducing electric power consumption in use; and reducing the heat produced during emission of the beam, also by virtue of the heat-dissipating function performed by supporting rod 13.

Secondly, using LED 9 advantageously provides for concentrating the projected beam solely on the opening of wash drum 7, thus reducing light dispersion outside the drum.

Thirdly, lighting device 8 has the major advantage of coding the operating status of washing machine 1 by means of a predetermined colour, thus enabling the user to determine the current operating condition of washing machine 1 quickly and easily, even at a distance from the machine, simply on the basis of the colour of the light projected onto the drum.

Clearly, changes may be made to the washing machine and lighting device as described and illustrated herein without, however, departing from the scope of the present invention as defined in the accompanying Claims.