WO2006018214A1 - Indicating device for an electrical appliance and method for producing this indicating device - Google Patents

Abstract

The invention relates to an indicating device (11) for an electrical appliance, in which an indicating unit (13) is provided that has an LED (19) with a transparent housing (21). This LED (19) or the housing (21) is provided with an opaque coating (28, 30) and, on a radiating side (26), is provided with a recess (23) in the form of a symbol. The coating and recess are designed so that light can radiate out of the housing only via the recess and so that they form a luminous indication. The housing (21, 121) is a transparent plastic housing in which a LED (19) is normally integrated. The coating is applied to the housing in a manner that prevents it from being detached. This eliminates the need for a subsequent application of coverings or the like to the LED during assembly of the indicating device. The invention also relates to a method for producing an indicating unit, during which a coating (28, 130, 230) is applied to the housing (25, 225), and a recess (23, 123, 223) is not covered by the coating.

Description

 description

Display device for an electrical appliance and method for producing such a display device

Field of application and state of the art

The invention relates to a display device according to the preamble of claim 1 and a method for producing a Anzeigeein¬ unit for such a display device.

In the case of hobs or other electrical appliances, illuminated displays are arranged under covers, for example in the case of a hob under a glass-ceramic cooking plate. A symbol represented by these indicator lights can be recognized through the cover and information or the like. Show.

From DE 198 02 571 it is known to use a lighting element in the form of an LED. In order to display a symbol with the light source forming a substantially punctiform or very small emission area, a display symbol mask is placed over the LED or attached thereto. The mask covers except for recesses, which correspond to the shape of the symbol to be displayed, the light source. Thus, only the recesses are transilluminated and there is a light phenomenon, which corresponds to the desired symbol. Thus, it can be avoided to arrange a plurality of substantially point-shaped light sources or LED of the contour of the symbol according to the representation of a symbol. However, when assembling a corresponding display, the additional step is that the mask must be fastened to the LED. Task and solution

The object of the invention is to provide an indicating device as well as a method for producing the same with which the disadvantages of the prior art can be avoided and in particular the additional assembly step can be eliminated.

This object is achieved by a display device having the features of claim 1 and a manufacturing method having the features of claim 13. Advantageous and preferred Ausgestal¬ lines of the invention are the subject of the other claims and wer¬ explained in more detail below. The wording of the claims is incorporated by express reference into the content of the description. Features that apply equally to the display device and the method are described in the following partly only once be¬, but apply independently for both. In addition to the display device, independent protection should also be claimed for the display unit itself and should exist.

According to the invention, it is provided that the display device has a luminous display unit with housing. This display unit is advantageous so to speak only provided with a single light unit or can not. different, but only jointly switchable Be¬ rich illuminate or bring to light. Advantageously, the Leucht¬ unit is an LED. The display unit is built into the housing or integrated therein or injected according to a conventional LED or the like, as it is known either in normal design or as an SMD component. The housing is substantially opaque, wherein it has a light-permeable recess in an emission direction from which it is viewed on the display device, or in a light-transmissive layer, coating or the like. a recess. This In turn, saving has the shape of the symbol which is to be represented by the display device by means of a light-emitting display.

Thus, in contrast to a normal LED with housing and a mask to be mounted thereon, which requires the additional mounting step, the housing of the LED is made directly opaque except for the recess. Through this, the LED lights up with an outcome that corresponds to that with the mask attached. The increased manufacturing costs that may be incurred as a result can be largely absorbed by automation. On the whole, however, this method makes it more cost-effective and, above all, safer in the production, since the assembly of masks or the like known from the prior art is more reliable. almost only by hand can be done. Incorrect assembly can cause malfunctions or at least an undesirable visual appearance.

The opacity of the housing can be achieved, for example, by means of a coating on the housing, which can be applied when the display unit is manufactured. It may be vor¬ seen, as is common in normal LED, that the housing is substantially transparent or herge¬ is made of transparent plastic. In a first version, it is subsequently provided with the coating except for the cut-out and thus rendered opaque except for the cut-out. In this version, therefore, no coating material is applied in the region of the recess or for the recess.

Alternatively, in the case of a second version, the recess or the passage of light can be subsequently produced by areawise removal of the coating material. For this purpose, for example, the top side of the housing in the emission direction can be formed continuously or flat or flat with coating applied thereto. TERIAL. This can be mechanically removed according to an embodiment of the invention, for example by engraving, scribing, cutting, boring or milling or the like. In a second embodiment of the invention, the recess can be machined out of the coating with a laser beam or the coating removed there be, so essentially thermally.

In a further version of the invention, the housing can have a projection on the side, which points in the emission direction, which has the shape of the recess. This supernatant consists of the transparent material of the housing or is an integral part of it. The coating can then be applied over a large area to the entire housing and thus also cover the supernatant. By sanding the side in the direction of radiation, the coating is then removed, so to speak, down to the supernatant. Although some layer thickness of the supernatant may be removed under certain circumstances, but this is harmless at least as long as a certain part of the supernatant remains. Around the supernatant is then still the coating, so that the housing can emit light only with the shape of the supernatant. In this type of manufacture, it is true that a different housing can be produced for each different symbol. However, the subsequent removal of the coating to the recess is easier.

In a modification of the invention, an abovementioned supernatant can also be used. The coating is then applied auf¬, which is not coated by a cover of the top of the supernatant in the emission direction. Thus, no subsequent removal of the coating is necessary. In a similar manner, in principle, a coating on the housing can be applied at least at the side pointing in the direction of radiation right at the beginning with the recess remaining free. Another possibility may be that a material is used as the coating, which is detached at light of specific wavelength and / or intensity. Then only the symbol to be represented needs to be projected onto the emission side of the completely coated housing, for example with a corresponding mask at the light source. There, the coating is removed and you get the desired recess.

On the one hand, an opaque plastic can be used as the coating as a thick layer. For this purpose, the housing of the display unit can, for example, be overmoulded in one work step. Thus, in any case, an opacity of the coating can be achieved. Alternatively, the coating may be a lacquer or the like. be, in which the housing is immersed, for example. It may also have desired properties, as listed here.

Advantageously, the display unit has a single LED and, as previously stated, can represent only a single symbol. This symbol is determined by the shape of the recess.

The term "recess" is not to be understood as a single interconnected surface. Below this, in the sense of the application, several individual areas or segments are also to fall, which, however, together form the symbol and also only a single symbol. They are always brought together by the display device only together or simultaneously for a single purpose.

These and other features are apparent from the claims and from the description and the drawings, wherein the individual features in each case alone or more in the form of Unter¬ combinations in one embodiment of the invention and other be realizable areas and can represent advantageous and self-protective embodiments for which protection is claimed here. The subdivision of the application into individual sections as well as subheadings does not limit the statements made thereunder in their generality.

Brief description of the drawings

Embodiments of the invention are shown schematically in the drawings and will be explained in more detail below. In the drawings show:

1 is a side view of an arrangement of a display device under a cover,

2 is a plan view of several embodiments of display units, each with different symbols or recesses,

3 shows a housing of a display unit in the ground state, which consists of transparent material,

4, the housing according to FIG. 3, which is painted according to a first method except for a recess, FIG.

5, the housing according to FIG. 3, which, according to a second method, is injection-molded to a recess with plastic, FIG.

6, the housing of FIG. 3, which is encapsulated with a third method with plastic, wherein the recess herausgear¬ is processed,

7 shows a modification of the housing similar to FIG. 3 with an overhang in the form of the recess as a ground state, FIG.

8, the housing according to FIG. 7, which according to a first method is injection-molded with plastic except for the projection;

9, the housing according to FIG. 7, which is completely injected with plastic around the projection and 10 shows the next processing step according to FIG. 9 with the plastic layer cut off.

Detailed description of the embodiments

In Fig. 1 is shown in side view, as a display device 11, consisting of a display unit 13 on a support 15, as spielsweise a circuit board, under a transparent cover 17, such as a glass ceramic plate of a glass ceramic Kochfel¬ is arranged , In this case, the display unit 13 has an LED 19 which has a housing 21 or is surrounded by it or is integrated therein. Down are symbolic by the carrier 15 An¬ connections 20 of the LED. In the case of a normal LED, for example, these can be the known feet made of metal wire. For SMD versions, electrical connections are provided at the side of the housing.

FIG. 2 shows three exemplary display units 13a-c. These each have different recesses 23a-c. These are used to show symbols corresponding to their shape by means of illumination, which will be explained in more detail below. Thus, the display unit 13a shows a large A 23a in the luminous state, the display unit 13b the symbol 23b for an activated additional heater at a hotplate of a glass ceramic hob and the display unit 13c a bar 23c or a minus sign.

In Fig. 3 it is shown how according to a first basic variant of the invention, a base housing 25 is present, which contains the dotted Darge presented LED 19. In particular, the base housing 25 is that in which the functional structure of the LED 19 is integrated or in which it is cast. This means that in Fig. 3 sozu¬ say a normal LED of transparent and possibly ein¬ dyed plastic is shown. As can be seen, the basic housing 25 in approximately cuboid, but it could also be rounded or hemispherical. It is provided that the upward wei¬ send side forms the emission side 26. This radiation side 26 is directed towards the cover 17 in FIG. 1, so that it is visible to an operator. It could also be rounded.

FIG. 4 shows how, according to a first version, the basic housing 25 according to FIG. 3 is covered with an opaque lacquer layer, which is illustrated by the hatching of the surface. This lacquer layer 28 may be applied for example by a dip coating process. Alternatively, it can be sprayed on. The lacquer layer 28 serves to prevent light from the LED 19 or light unit located in the base housing 25 from being exposed to the outside. Under certain circumstances, the lacquer layer 28 may be dispensed with at the underside opposite the emission side 26, which, however, also depends on the intended use. In any case, it should be avoided that light exits at the bottom and so can be seen laterally.

On the emission side 26, a recess 23 similar to the recess 23c of FIG. 2 is provided. In this area, no lacquer layer 28 is present, so that when the LED 19 is lit, a symbol corresponding to the shape of the recess 23 lights up and can be seen from above. To produce the recess 23, for example, a kind of cover can be applied before painting in the form of the recess, which is subsequently removed.

In Fig. 5 it is shown how the base housing 25, which is represented by the dashed line, surrounded by a relatively thick and lichtundurchläs¬ sige plastic layer 130 and is encapsulated. Essentially, this plastic layer 130 corresponds to the lacquer layer 28 according to FIG. 4, only the application method and the material is different. Here, too, a cutout 123 similar to that of FIG. 3 is provided on the emission side 126. At this recess 23 no plastic layer 130 is present, so that light can escape from the base housing 25 and the resulting housing 121. The Ausspa¬ tion 123 can be generated for example in a corresponding encapsulation by a projection in the injection mold, which reaches up to the surface of the coated housing 25 and prevents that here the plastic layer is applied.

Another way to achieve the recesses 23 and 123 shown in FIGS. 4 and 5, may be to edit according to FIG. 6 with a laser 32 or a cutter 34 a self-contained lacquer layer 28 or plastic layer according to the recess 23 or to remove except for the basic housing or its emission side. This creates subsequent processing costs. For this reason, the covering or coating of the basic housing with the light-impermeable layer 28 is simpler. In such a processing, it should be ensured that neither the laser 32 nor the milling cutter 34, which actually acts on the upper side of the basic housing 25, destroy the LED or even the LED therein to such an extent that a scratched surface causes it no more light can be generated or only too weak can escape. In particular, when using lacquer layers 28, however, it is advantageously possible and technically manageable to achieve that the lacquer layer can be detached with relatively little energy from the laser 32, without adversely affecting the basic housing or the material.

FIG. 7 shows an output alternative to the basic housing 25 according to FIG. 3. Here, at the top of the base housing 225 on the Ab¬ beam side 226, a projection 224 is formed. Advantageously, it consists of the same transparent material as the housing 221 itself and is manufactured in one piece in the same production or injection process. According to FIG. 8, on the one hand, the housing 221 can be surrounded or surrounded by a lacquer or plastic layer 230 approximately in accordance with FIG. 5 such that the thickness of the layer 230 corresponds approximately to the height of the projection 224 above the emission side 226 , at least on the radiation side itself. This causes the entire housing 221 is um¬ injected with plastic as in the previous figures and thus no light passes through. Only the top of the supernatant 124 is still free and, as it were, surrounded by a recess 223 in the plastic layer 230. Thus, only at the supernatant 224 can light escape and the desired symbol be displayed. It is not considered disturbing if, as shown, the supernatant 224 even projects beyond the plastic layer 230. As a result, a representation of the illuminated display only takes place in the form of the symbol 223 in the form of the projection. Here, there is the advantage that subsequent processing can be eliminated and, in particular, the layer thickness tolerances do not have to be so exact.

In Fig. 9, an alternative method is shown. Here, the base housing 325 is coated with a plastic layer 330 such that it also covers the entire projection 324 and in particular des¬ sen top. Subsequent grinding with a grinding device 334 removes so much of the layer 330 that, according to FIG. 10, at least the upper side of the overhang 324 is exposed. Since the remaining housing 321 is still surrounded by the layer 330, light can again emerge only on the projection 324 with the outline of the recess 323 for the desired luminous symbol display.

Thus, it can be stated as a whole that in FIGS. 3 to 6 either an opaque coating is applied to the LED housing. is brought, which leaves the recess already or exposes these later by editing or partial removal of the coating. Alternatively, as shown in FIGS. 7 to 10, by providing a supernatant or the like. as an integral part of the housing already given in symbol form and ensured that at this point no coating covers the housing or the supernatant. The covering layer is laid around the projection in a corresponding shape of the recess.

According to the first method according to FIGS. 3 to 6, unlimited flexibility in the representation of a symbol or the like is particularly in the subsequent removal of the coating. given that only the machining machines according to FIG. 6 have to be reprogrammed. It can be used a single and always the same housing for the LED.

In the second method according to FIGS. 7 to 10, an LED with in each case a different housing and a corresponding projection is produced for each symbol to be represented differently. However, here the coating processes can be carried out more easily or a subsequent processing by milling a coating over the supernatant is always exactly the same and can be carried out faster.

In both methods, the coating is permanently applied to the housing, namely already on the production side before mounting the display unit on a printed circuit board or the like. This eliminates the step during assembly. Furthermore, the cover can not be dropped by carelessness or repelled.

Claims

claims A display device (11) for an electrical appliance with a luminous display unit (13, 113, 213, 313), preferably with an LED (19), wherein the display unit has a housing (25, 225) in which it is installed or therein is integrated or injected, da¬ characterized in that the housing is substantially licht¬ opaque and in a radiation direction a lichtdurchläs¬ sige recess (23, 123, 223, 323), wherein the Ausspa¬ tion the shape of a dargestellellenden by light display Sym¬ bols (23a - c) has. 2. Display device according to claim 1, characterized by a opacity by a coating (28, 130, 230, 330) on the housing (25, 225), wherein preferably the Materi¬ al of the housing is otherwise transparent, in particular plastic is , 3. Display device according to claim 2, characterized in that the recess (23, 123, 223) is free of the coating (28, 130, 230) by non-application of coating material. 4. Display device according to claim 2, characterized in that the recess (23, 323) is free of the coating (28, 130, 323) by subsequent removal of the coating, preferably only removal of the coating in the form of Ausspa¬ tion. 5. Display device according to claim 4, characterized in that the coating material (28, 130, 323) at the Ausspa- tion (23, 323) by milling (34) or drilling is mechanically removed. 6. Display device according to claim 4, characterized in that the coating material (28, 130) on the recess (23) by laser action (32) is removed. 7. Display device according to one of the preceding claims, characterized in that the housing (225, 325) on the side (226, 326) of the emission direction, a projection (224, 324) in the form of the recess (23, 323), wherein The coating (230, 330) is attached to the overhang in such a way that approximately a flat upper surface is formed, to which both the supernatant and the coating approximate. 8. Display device according to one of the preceding claims, characterized in that the housing (25, 125, 225) on the other sides than that in the emission direction (26, 126, 226, 326) a coating (30, 130, 230, 330 ) of the same kind. 9. Display device according to one of the preceding claims, characterized in that the coating lichtundurchläs¬ sigen plastic (30, 130, 230, 330) as a thick layer, wherein preferably the housing (25, 225, 325) with the plastic encapsulated is. 10. Display device according to one of claims 1 to 8, characterized in that the coating is an opaque lacquer (28), preferably applied by dip coating method. 11. Display device according to one of the preceding claims, characterized in that the display unit (13, 113, 213, 313) has a single LED (19) and for representing a single symbol in the form of the recess (23, 123, 223, 323) aus¬ is formed. 12. Display device according to one of the preceding claims, characterized in that the recess (23b) has a plurality of non-contiguous surface areas which together represent a single symbol or symbol. 13. A method for producing a display unit (13, 113, 213, 313) for a display device (11) according to any one of the preceding claims, characterized in that on the housing (25, 225), the coating (28, 130, 230) applied and the recess (23, 123, 223) remains free of the coating. 14. The method according to claim 13, characterized in that a full-surface coating (28, 130, 330) on the housing (25, 225) is applied and then the recess (23, 323) is cleared in the desired form of the coating. 15. The method according to claim 14, characterized in that the recess (23, 323) is freed by mechanical action tet, in particular by milling (34, 334) or drilling. 16. The method according to claim 14, characterized in that the recess (23) is cleared by structuring with a laser (32), wherein preferably the coating (28, 130) in the Be¬ rich of the recess is evaporated. 17. The method according to claim 13 or 14, characterized in that the housing (225, 325) has a projection (224, 324) made of translucent material in the emission direction in the form of the recess (223, 323) and at least on this side (226, 326) of the housing, the coating is applied, wherein vor¬ preferably the coating is first overlapping applied over the recess (323) and is then removed flat. 18. The method according to any one of claims 13 to 17, characterized gekenn¬ characterized in that the coating (130, 230, 330) is applied by plastic overmolding, advantageously in a single Vor¬ gang. 19. The method according to any one of claims 13 to 17, characterized gekenn¬ characterized in that the coating (28) is applied by painting.