EP2462070A1

EP2462070A1 - Household appliance cover plate comprising an internal laser engraving

Info

Publication number: EP2462070A1
Application number: EP10727440A
Authority: EP
Inventors: Miguel Angel BUÑUEL MAGDALENA; Jesús CEAMANOS GAYA; Francisco Javier Ester Sola; Jose-Ramon Garcia Jimenez; Sergio Llorente Gil; Alfonso Lorente Perez; Carlos Vicente Mairal Serrano; Rosa Isabel Merino Rubio; Víctor Manuel ORERA CLEMENTE; José Ignacio Peña Torre; Rene Schmalenstrot; Daniel Sola Martinez
Original assignee: BSH Bosch und Siemens Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2009-07-14
Filing date: 2010-07-02
Publication date: 2012-06-13
Also published as: ES2377695B1; WO2011006773A1; CN102574739A; ES2377695A1

Abstract

The invention relates to a household appliance cover plate made of a glass or glass ceramic material having an internal laser engraving (12). In order to reduce the variety of components, the invention proposes that the glass or glass ceramic material is black.

Description

Domestic appliance cover plate with a laser interior engraving

The invention relates to a household appliance cover plate made of a glass or glass ceramic material with a laser interior engraving according to the preamble of claim 1.

From the prior art it is known to incorporate brand logos in corner areas of household appliance cover plates by the known per se technique of laser engraving in the glass or glass ceramic material. In laser engraving, laser light is focused at a point inside the glass or glass-ceramic material, so that the material heats up strongly there. On heating and / or cooling, microscopic cracks and / or a microcrystalline structure are formed in a precisely defined region having a size of several μm to several hundred μm. This will change the

Refractive properties in this range, resulting in light scattering and / or reflection. With a laser, such scattering centers for the light can be specifically incorporated in such a way that a trademark is created. Furthermore, it is known to illuminate such internal laser engravings with light-emitting diodes, which may be arranged on the side edge of the glass-ceramic plate. To create the impression of a floating brand logo, clear and completely transparent glass-ceramic materials are used. These are expensive and / or sensitive compared to black glass ceramic.

The invention is in particular the object of opening up new design options for a home appliance cover plate with laser engraving.

The object is achieved in particular by a household appliance cover plate according to claim 1. Advantageous embodiments and further developments emerge from the subclaims. The invention is based, in particular, on a household appliance cover plate made of a glass or glass-ceramic material with a laser interior engraving. It is suggested that the glass or glass ceramic material is black. Black glass-ceramic, which is marketed, for example, under the trademark CERAN, is inexpensive and robust and can be produced with vanishing or very low coefficients of thermal expansion. Due to the limited transparency of this material, it has not previously been used to make a domestic appliance cover plate with laser engraving. Surprisingly, however, it has been found that very impressive effects can be achieved by the combination of black glass ceramic and a laser engraving, in particular when the internal laser engraving is illuminated. The brilliant laser engraving stands out from the black background particularly well. The limited transparency of the semitransparent material is surprisingly hardly disturbing. Although the advantages of the invention in particular in cooktop cover plates for induction cooktops come to fruition, the inventive idea is in principle applicable to cover plates of other household appliances.

The glass or glass-ceramic material may in particular be semitransparent and colored black by means of a metal doping and / or have a black coating on its rear side in order to achieve an overall black impression.

In particular, a glass ceramic of lithium-aluminum silicates with a particularly low coefficient of thermal expansion into consideration.

In addition to the different optical properties, areas of the cover plate with laser engraving also have an influence on the thermal conductivity of the material.

In particular, phonons are reflected at the interface between engraved and non-engraved areas of the glass or glass-ceramic material, so that the

Thermal conductivity is reduced. The microscopic cracks and crystal interfaces of the engraved areas also act as scattering centers that reduce overall thermal conductivity. The influence of the glass interior engraving on the thermal conductivity has been refrained from arranging interior glass engravings in areas of high heat flux density, as it was feared the emergence of strong thermal gradients, which could cause damage in conjunction with the mechanical weakening of the material by the inner engraving. Another aspect of the invention is the use of an internal laser engraving as a heat shield. It is proposed that the heat shield of a household appliance cover plate is designed as a surface laser interior engraving in the interior of the glass or glass ceramic material. As a result, it is possible to dispense with a heat shield designed as a separate component, or such a heat shield can be made more cost-effective, as a result of which the variety of components and the production costs of the domestic appliance can be reduced. The use of internal laser engraving as a heat shield can also bring advantages in completely transparent or clear glass-ceramic materials and is not limited to black glass-ceramic materials.

A noticeable effect can be achieved if the laser engraving covers at least 30% of the area of a heating zone covered by the cover plate. The heat shield is particularly desirable in heating zones of induction hobs. A heat-shielding effect can be achieved without the transparency of the

To affect the cover plate too much, if the internal laser engraving of hatching lines with a line spacing of at least 0.5 mm is constructed.

Parallel to the plane of extension of the household appliance cover plate, the surface laser internal engraving can be constructed in particular of hatching lines with a line spacing of at least 0.09 mm. As a result, infrared radiation is effectively shielded without unduly weakening the mechanical stability of the cover plate. The laser engraving can also include a marking and / or lettering. Partial transparency may be maintained in areas where this is desired when the laser engraving surrounds a viewing window. This is particularly in the application of the invention in cover plates for covering a display into consideration, so as not to affect its visibility. A three-dimensional visual impression can be achieved and several layers with scattering centers and thus a better heat shield can be realized when the heat shield extends over several parallel staggered layers formed by an internal laser engraving. The necessary impact resistance of the household appliance cover plate can be ensured if a distance between the laser internal engraving and a surface of the cover plate is at least 1 mm. In order to further improve the heat shield, it is proposed that a

Total surface of the laser engraving is at least 20 cm ² . As a result, a clearly noticeable heat shielding can be achieved.

Furthermore, a domestic appliance device with a domestic appliance cover plate according to the invention and at least one lighting unit is proposed, which is intended to illuminate at least one partial area of the laser interior engraving. A "lighting unit" is to be understood in particular as meaning an electrical unit which at least partially converts electrical energy into visible light, wherein the unit is preferably heated by a heating unit or preferably by a heating unit may be formed by a unit formed separately from a heating unit. The illumination unit may comprise various illuminants that appear appropriate to the person skilled in the art, but preferably comprises at least one light-emitting diode. The illumination unit emits at least one wavelength of light for which the cover plate has a light transmission of more than 10%, advantageously more than 30%, particularly advantageously more than 50% and in particular more than 70%. A "light transmission" for a specific wavelength of light is intended here and below to mean in particular a ratio of a light intensity of the light wavelength emitted by an infinitely extended light source at a first point to a light intensity of the considered light wavelength at a second point at a distance of 20 mm, in particular 10 mm, advantageously of 5 mm and particularly advantageously 1 mm, the first point being arranged closer to the light source than the second point, the design according to the invention makes it possible to achieve structurally simple optical effects comprise a luminous means which is intended to emit different wavelengths of light and / or comprise at least two luminous means which emit different wavelengths of light i wavelengths of light whose relative difference is greater than 2%, in particular greater than 5%, advantageously greater than 10% and particularly advantageous is greater than 20%. As a result, complex optical color effects can be achieved. Advantageously, the lighting unit is provided to illuminate a label, in particular a brand name, and / or a marking, in particular a brand logo. As a result, a high recognition value and an advantageous advertising effect can be achieved.

Furthermore, a domestic appliance device with a domestic appliance cover plate according to the invention and at least one diffuser unit is proposed, which is arranged at least partially between the illumination unit and the partial area and which is intended to at least partially scatter light from the illumination unit. A "diffuser unit" is to be understood as meaning, in particular, a unit which is at least translucent and preferably has scattering centers for at least one wavelength of light emitted by the illumination unit less than 60%, advantageously less than 40% and particularly advantageously less than 20%, that the diffuser unit "is at least partially arranged between the illumination unit and the subarea" should be understood to mean that at least parts of the diffuser unit of at least one of the illumination unit are penetrated in the direction of the subregion of the laser interior engraving emitted light beam. The fact that the diffuser unit is intended to "at least partially scatter light from the illumination unit" is to be understood as meaning that at least one wavelength of light emitted by the illumination unit is scattered in the diffuser unit and the diffuser unit thereby preferably acts like a diffuse light source for this wavelength of light Such an embodiment makes it possible to achieve an impression of an extended and / or diffuse light source, and diffuse illumination of the subarea of the laser interior engraving can be achieved.Preferably, the diffuser unit is formed by a unit separate from the household appliance cover plate. However, it may alternatively or additionally be formed by the household appliance cover plate itself.

Further advantages emerge from the following description of the drawing. In the drawings, embodiments of the invention are shown. The drawing, the description and the claims contain numerous features in combination. Of the A person skilled in the art will expediently also consider the features individually and combine them into further meaningful combinations.

Show it:

1 is a plan view of a household appliance device with a hob cover plate with four heating zones and a lighting unit,

1a is a sectional view of the domestic appliance device of FIG. 1 along the line Ia-Ia according to an alternative embodiment,

Fig. 2 is a sectional view of the cover plate of FIG. 1 along a

Line N-II with a temperature sensor and an internal laser engraving,

Fig. 3 is a cover plate according to an alternative embodiment

of the invention with a multi-layer internal laser engraving, and

Fig. 4 is a front cover plate of a baking oven door after another

Embodiment of the invention.

1 shows a domestic appliance device with a domestic appliance cover plate designed as a hob cover plate for an induction hob from a black glass or glass-ceramic material made of lithium aluminum silicates. The cover plate comprises an integral heat shield 22 incorporated in the glass or glass ceramic material for shielding a heat input of a hot cooking pot, which may be placed on the cover plate. The heat shield 22 prevents the radiated heat from the pan heat the cover plate and thus the electronics of the induction cooktop and can cause damage.

The cover plate closes in a conventional manner, not shown here cooktop housing of the induction cooktop from above. In the cooktop housing, the power electronics of the induction cooktop and the inductors for inductive heating of the set up on the hob cookware elements are arranged. For inductive heating of the cookware elements, the inductors generate high-frequency alternating magnetic fields, which in turn generate the high-frequency eddy currents in the ferromagnetic induce the bottom of the cookware. The dissipation of these eddy currents heats the ferromagnetic material of the cookware tray.

The cover plate shown in Fig. 1 is a cover plate for an induction cooktop with four heating zones 10a to 10d, in whose region in each case an inductor is arranged or a plurality of inductors are arranged. The shape, size and structure of the heating zones 10a-10d may be selected in a manner that appears appropriate to one skilled in the art. In the area of the heating zones 10a to 10d, a flat internal laser engraving 12 is provided in the interior of the glass or glass ceramic material, which has the structure of concentric rings in the exemplary embodiment shown in FIG. The laser interior engraving 12 covers approximately 80 to 90% of the total area of the respective heating zone 10a to 10d. The heating zones 10a to 10d are circular and the diameter of the heating zones 10a to 10d corresponds to the diameter of the respective inductor. This is between 18 cm and 30 cm, whereby in so-called matrix cooktops also significantly smaller inductors can be used.

Microscopically, the laser internal engraving 12 is formed in a plane which is parallel to a top 32 and a bottom 34 of the cover plate. Within this

Level is the laser interior engraving 12 of hatching lines with a line spacing of approx.

0.09 mm. In a partial region 26 of the laser internal engraving 12 is a mark

14 or inscription incorporated. In the embodiment shown in FIG. 1, the marking 14 is arranged in a corner region of the cover plate, so that the

Mark 14 is not part of the heat shield 22 formed by the laser engraving 12. Through the formed by the glass ceramic material black background occurs

Mark 14 particularly rich in contrast.

The household appliance cover plate designed as a hob cover plate is part of a household appliance device which has a lighting unit 24 which is provided to illuminate the partial region 26 of the laser interior engraving 12. Furthermore, the domestic appliance device has a diffuser unit 27, which is arranged between the illumination unit 24 and the partial area 26 and which is provided to at least partially scatter light from the illumination unit 24. The lighting unit 24 has a red LED 28. The lighting unit 24 is arranged laterally on a side edge 30 of the household appliance cover plate and provided to radiate light through the diffuser unit 27 through the side edge 30 in the cover plate. The diffuser unit 27 gives the impression of an extended, diffuse light source. The light emitted by the illumination unit 24 in the cover plate passes partly directly and partially by one or more total reflection at the top 32 and the bottom 34 of the cover plate to the portion 26 of the laser engraving interior 12. The laser interior engraving 12 is thus in Illuminated portion 26 in an at least substantially parallel to the top 32 of the cover plate direction. As a result, a three-dimensional appearance of the marking 14 is achieved, which gives the impression that the marker 14 would float freely in the space below the top 32 of the cover plate. As an alternative to the red light-emitting diode 28, any other light-emitting means is also possible which emits at least one light wavelength for which the glass or glass-ceramic material is at least partially transparent. Furthermore, the lighting unit 24 may also be provided to radiate light directly through the side edge 30 in the cover plate. As a result, further special optical effects can be achieved.

Alternatively or additionally, a lighting unit 24 'can also be arranged on the underside 34 of the cover plate, as shown in Fig. 1 a in a sectional view of the domestic appliance device of FIG. 1 along a line Ia-Ia. The partial region 26 of the laser internal engraving 12 is here illuminated by the underside 34 in the direction of the upper side 32 of the cover plate. The illumination unit 24 'has two red LEDs 28' and 29 '. Between the illumination unit 24 'and the underside 34 of the cover plate, a diffuser unit 27' is arranged, which is intended to scatter the emitted light of the illumination unit 24 'so that the impression of an extended, diffuse light source is created. In this embodiment, an inverted marker 14 can be achieved in which an environment of the marker 14 appears illuminated, but the marker 14 stands out from the illuminated environment. Alternatively or additionally, the diffuser unit 27 'may also be formed by parts of the cover plate. In this case, the light transmittance of the glass-ceramic material of the cover plate for that of the

Lighting unit 24 'emitted light wave range sufficiently low, thereby achieving a high light scattering in the cover plate. Alternatively, the light-emitting diodes 28 'and 29' of the illumination unit 24 'can also emit light in different light wavelength ranges. Through the diffuser unit 27 'can then be a color mixture can be achieved, whereby any color effects can be achieved. Furthermore, it is conceivable that the light-emitting diodes 28 'and 29' are switched on and off in succession, whereby a color change of the marking 14 can be achieved. Furthermore, the illumination unit 24 'can also have more than two illumination means. Furthermore, an embodiment of the household appliance device without diffuser unit 27 'is conceivable. The internal laser engraving 12 arranged in the region of the heating zones 10a to 10d shields the heat generated in the bottom of the cookware element and prevents this heat from penetrating into the interior of the hob housing. The phonons are reflected at an interface between the unprocessed glass or glass-ceramic materials and the glass-ceramic material forming the inner engraving 12 and / or at an interface between the glass-ceramic material forming the inner engraving 12 and the unprocessed glass-ceramic material. The hatching is generated by a zigzag movement of the focal point of the laser inside the glass or glass ceramic material. In particular, a pulsed laser can be used to produce the internal laser engraving.

Fig. 2 shows a sectional view of the cover plate of Fig. 1 along a line M-l lmit the internal laser engraving 12 and a temperature sensor 16, as it is located in the center of each of the heating zones 10a to 10d. In an environment of the temperature sensor 16, the internal laser engraving 12 is recessed to prevent an influence of the heat shield function on the temperature measurement. Incidentally, the internal laser engraving surrounds the temperature sensor 16 completely. Additionally or alternatively, a temperature sensor 17 may also be provided below the laser inner engraving 12 on the underside 34 of the cover plate, as is indicated schematically in Fig. 2.

The thickness of the cover plate is about 4 mm and a minimum distance of the laser inner engraving 12 from the top 32 and the bottom 34 of the cover plate is about 1 mm.

Fig. 3 shows an alternative embodiment of the invention, in which the laser inner engraving 12 extends over a plurality of mutually parallel staggered layers 12a, 12b, 12c, which form different parts of the laser interior engraving. A distance between the layers 12a, 12b, 12c is at least 0.5 mm in order to ensure a sufficient stability of the cover plate. 4 shows a further possibility of using the aspect of the heat shield by means of the laser internal engraving 12 of a cover plate. The cover plate with the laser engraving 12 is used as a front cover plate of a oven door. The laser interior engraving 12 is particularly dense in an edge region 18 of the front cover plate, so that the edge region 18 leaves open a viewing window 20, through which the user can look into the cooking chamber of the oven closed by the oven door. In the area of the viewing window 20, additional thermal insulation can be achieved by a less dense laser internal engraving 12, wherein to ensure sufficient transparency in this area, a line spacing between the hatching lines of the laser internal engraving should be at least 0.5 mm.

The integrated heat shield 22 according to the invention can be produced with virtually any glass ceramic material available on the market. Low thermal expansion glasses such as borosilicate glass or the material known by the trade name BOROFLOAT may also be used.

reference numeral

10a heating zone

10b heating zone

10c heating zone

10d heating zone

12 laser engraving

14 mark

16 temperature sensor

17 temperature sensor

18 border area

20 viewing window

22 heat shield

24 lighting unit

26 subarea

27 diffuser unit

28 LED

29 LED

30 side edge

32 top

34 bottom

Claims

claims

1. Household appliance cover plate made of a glass or glass-ceramic material and a laser interior engraving (12), characterized in that the glass or Glaske- ramikmaterial is black.

2. Household appliance cover plate according to claim 1, characterized in that the

Laser interior engraving (12) at least 30% of an area covered by the cover plate heating zone (10a to 10d) covered.

3. Household appliance cover plate according to one of the preceding claims, characterized in that the laser internal engraving (12) is constructed of hatching lines with a line spacing of at least 0.5 mm.

4. Household appliance cover plate according to one of the preceding claims, characterized in that the planar laser interior engraving (12) is constructed of hatching lines with a line spacing of at least 0.09 mm.

5. Domestic appliance cover plate according to one of the preceding claims, characterized in that the internal laser engraving (12) comprises a marking (14) and / or labeling.

6. Household appliance cover plate according to one of the preceding claims, characterized in that the heat shield (22) comprises a plurality of mutually parallel staggered layers extending laser internal engraving (12).

7. domestic appliance cover plate according to one of the preceding claims, characterized in that the internal laser engraving (12) in the region of a temperature sensor (16) is recessed.

8. domestic appliance cover plate according to one of the preceding claims, characterized in that a distance between the laser inner engraving (12) and a surface of the cover plate is at least 1 mm.

9. domestic appliance cover plate according to one of the preceding claims, characterized in that a total surface area of the laser engraving (12) is at least 20 cm ² .

10. Domestic appliance device with a domestic appliance cover plate according to one of the preceding claims, characterized by at least one illumination unit (24, 24 '), which is intended to illuminate at least a portion (26) of the laser engraving interior (12).

1 1. Home appliance device with a household appliance cover plate according to claim 10, characterized by at least one diffuser unit (27; 27 ') which is at least partially disposed between the illumination unit (24; 24') and the partial area (26) and which is provided To at least partially scatter light from the illumination unit (24; 24 ').

12. Induction hob with a household appliance cover plate according to one of claims 1 to 9 or induction hob with a home appliance device according to claim 10 or 1 first