Control device, in particular for a domestic appliance

The present invention relates to a control device having at least one front panel, at least one button panel arranged behind the front panel, and at least one switch responsive to a user's touch of a switchable area on a front side of the front panel in front of said switch. The switch includes at least one light source element arranged at a rear side of the button panel illuminating the rear side of the front panel, and at least one reflector element arranged behind the button panel and the light source element to reflect the light to the rear side of the button panel. The button panel includes at least one cut out that corresponds with the switchable area of the switch or more switchable areas of neighbored switches, so that the light can pass through the cut-out and the front panel to be out of the control device.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a control device, in particular for a domestic appliance. Further, the present invention relates to a button panel for said control device. Moreover, the present invention relates to a method for assembling a control device, in particular for a domestic appliance.

2. Description of the Prior Art

An appliance includes often a control device with one or more touch switches. For example, said touch switches may be of a capacitive type, an inductive type, an optical type, an infrared type or a funk type. In other words, the touch switches do not contain any mechanical elements. None of the components of the touch switches is distorted. The touch switches of the control device of an appliance, in particular of a domestic appliance, should be illuminated in order to indicate the corresponding operation and/or a parameter relating to said switch or corresponding operation. Further, the illumination should also be sufficient, if the environmental illumination conditions are disadvantageous. For this purpose, known touch switches are lightened by illumination means.

Furthermore, another problem is that the illumination of a switchable area of the switch is not homogeneous enough. Some parts are intensively illuminated, while other parts are quite dark, since touch switch may include one or more electrical tracks arranged on the printed circuit board. Said electrical tracks are usually made of copper or other opaque materials. In particular, the electrical tracks of the touch switch are provided as sensor for detecting the proximity or touch of a human finger. Further, the electrical track may be provided as antenna for detecting infrared or radio signals. However, the electrical tracks may cross the illuminated area of the touch switch and constrain the illumination. Such a design is even more complex and expensive and results in higher energy consumption, since some light is absorbed by a switchable area.

EP 1 985 930 B1 discloses a control device with a front panel for a domestic appliance. At the rear side of the front panel are one or more switches having at least one illumination element. The front panel is made of transparent glass or plastics with printed icons. The illumination element consists of at least one light source element arranged on the rear side of a printed circuit board and at least one reflector element for indirectly lightning of a rear side of the switch. The reflector element covers the light source element and the illuminated area from behind. The control panel must be of a transparent material in order to allow the light passing through at least a part of the switchable areas. However, it is difficult to find any suitable material for a button panel, which is transparent on the one hand and able to carry electric and/or electronic components. Further, the control device has a complex design, so that the costs for the illumination of the switch are relatively high. In particular, the costs of a transparent material for the button panel and printed circuit board are high.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved control device with a front panel, which front panel may be used as a printed circuit board and/or a carrier for components of the control device. The control device and its components shall have low complexity and be aesthetically attractive.

The object of the present invention is achieved by the control device according to claim1.

According to the present invention the button panel includes at least one cut-out, wherein the cut-out corresponds with one switchable area of the switch or with more switchable areas of neighboured switches, so that the light can pass through the cut-out and the front panel out of the control device.

The main idea of the present invention is at least one cut-out in the button panel, wherein the cut-out is arranged behind a switchable area. The light through the button panel can pass through the cut-out and the front panel. It is not necessary that the button panel is made of a transparent material. The material of the button panel has no influence to the illumination of the switches and the control device. The material for the button panel may be selected independently of its optical properties. This allows a reduction of the costs. In particular, the button panel may be also used as a printed circuit board carrying electric and/or electronic elements of the control device.

According to a first preferred embodiment of the control device of the present invention, the reflector element is formed as a half-shell and includes a first reflecting zone and a second reflecting zone, wherein the first reflecting zone is flat and arranged behind the at least one light source element and the second reflecting zone is concave shaped and arranged behind the cut-out.

Still preferably, the at least one light source element is arranged beside, below and/or above the cut-out. The indications “beside, below and/or above the cut-out” as used herein refer to an essentially vertical arrangement of the control device on a frontal face of the domestic appliance.

The flat first reflecting zone that is arranged behind the light source element and the concave shaped second reflecting zone that is arranged behind the cut-out allow a homogeneous illumination of the switch and/or the switchable area and prevent hot spots thereon.

Preferably, the button panel is made of a non-transparent material. The cut-out or cut-outs allow the use of the non-transparent material for the button panel. The material of the button panel has no influence to the illumination of the switch or switchable area. The material for the button panel may be selected independently of its optical properties. This contributes to a reduction of the costs.

In a similar way, at least that portion or those portions of the front panel arranged in front of the switch or switches are made of a transparent or semi-transparent material. For example, the whole front panel is made of a transparent or semi-transparent material, and an opaque lacquer is applied onto these portions, which are not in front of the switches. Additionally, a clear lacquer may be applied onto those portions in front of the switches. The opaque and clear lacquer may be applied onto the front side and/or the rear side of the front panel.

A printed icon can be provided inside a clear area of the front panel that is not covered by an opaque lacquer and that corresponds at least in its location and preferably also in its shape to a cut-out of the underlying button panel that comprises a switch. The clear area of the front panel that comprises the printed icon can be surrounded by at least one opaque printed non-switchable area so that the light that is emitted from a light source element can only shine through the front panel in the clear area thereof. In that way, the printed icon inside the clear area of the front panel is illuminated and provides a visible indication on the front side of the front panel of a touch-sensitive switch which is provided below the front panel at the corresponding position of the cut-out in the button panel. The printed icon preferably has in addition a suitably chosen design that is indicative of the functionality of the corresponding switch.

According to the present invention, said visible indication of a switch can be provided on the front panel without any physical change of the front surface of the front panel in its area that corresponds to said switch. In that way, the present invention provides a considerable advantage by the uniform aesthetical appearance of the front panel and in an increased lifetime endurance of the areas of the front surface of the front panel which correspond to switches.

The front panel is preferably formed essentially of a transparent or semi-transparent material that can be covered, preferably on most of its area, by an opaque lacquer that corresponds to one or more printed non-switchable areas of the front panel. The switchable areas of the front panel are essentially left free of the opaque lacquer but may be covered by a transparent lacquer. A switchable area can typically have a rectangular shape that corresponds in its location, its shape and its size to a rectangular cut-out of the underlying button panel which comprises a touch-sensitive switch. But a variety of suitable other shapes of cut-outs in the button panel and of the corresponding switchable areas of the front panel, such as for example a circular shape, are also possible. The switchable areas should essentially match in the relative location the corresponding cut-outs of the underlying button panel in order to allow a secure actuation of the switches by the user on the front panel. However, the shape and the size of a switchable area can but need not closely match the shape and size of the corresponding cut-out. Essentially, the shape of a switchable area that is illuminated via the corresponding cut-out should allow a user to identify safely the position on the front panel that corresponds to the switch. However, the choice of the relative shapes and sizes of the cut-outs and the switchable areas and can be influenced by aesthetical considerations. For example a close match in shape and size of both a cut-out in the button panel and a corresponding switchable area of the front panel will lead to a rather sharply delimited and essentially uniformly illuminated switchable area on the front panel. A switchable area that is bigger than the underlying cut-out of the button panel may have a fainter illumination in its border region, etc.

A switchable area of the front panel that is essentially left free of the opaque lacquer can preferably comprise a suitably chosen printed icon that can be indicative of the functionality of the corresponding switch. The printed icons can be chosen for example from suitable icons that are per se known in the prior art. According to the invention, a printed icon can be formed in a variety of ways inside a switchable area of the front panel. For example, a printed icon can be printed with an opaque lacquer inside a switchable area that is otherwise left free of the opaque lacquer of the surrounding printed non-switchable area of the front panel. In alternative, a switchable area can also be covered by the opaque lacquer of the surrounding non-switchable area for almost all of its own area with the exception of the printed icon itself which is left transparent in that it either is not covered by any lacquer or in that it is covered by a transparent lacquer. Such an embodiment of a transparent printed icon is actually one example of the above-disclosed situation wherein a switchable area does not match precisely in its size and its shape to the underlying cut-out of the button panel. However, also in that case the relative positions of the transparent printed icon and the underlying cut-out in the button panel match suitably to safely identify the position on the front panel of corresponding switch.

Further, the button panel and/or the front panel may be or include a printed circuit board. This reduces the number of components of the control device.

Moreover, the button panel may include at least one conductor track. The conductor track may be connected to the switch and/or to other components of the control device. Also a plug may be provided for an electrical connection to other parts of the appliance.

At least one conductor track may enclose the cut-out on a front side or rear side of the button panel, wherein at least one conductor track is responsive to touching the switchable area in front of the cut-out. For example, this conductor track may be used a sensor for detecting a human finger touch the front panel.

In particular, the button panel may be provided for carrying electric and/or electronic elements. Thus, the button panel may be the carrier of the circuit of the control device. The front panel covers the front side of the control device. The front panel may be made of transparent glass or plastics, wherein printed icons may be applied on the switchable areas. In a similar way, non-switchable areas may be printed by opaque ink. Each of the printed icons and/or the printed non-switchable areas may be printed to the front side and/or to the rear side of the front panel.

According to a second preferred embodiment of the control device of the present invention at least part of and preferably all of the printed icons are printed on the rear side of the front panel and/or at least one, preferably all printed non-switchable areas are printed on the rear side of the front panel. At the rear side of the front panel, the printed icons and the printed non-switchable areas are protected by the front panel against any abrasion by the user who touches the front side of the front panel for actuating a switch or for cleaning the front panel. In addition, the aesthetic appearance of the front panel is better if the printed icons and/or the printed non-switchable areas are applied on the rear side of the front panel.

Furthermore, at least a part of the electric and/or electronic elements may be arranged around the at least one cut-out. This allows a compact structure of the control device.

The switchable area of the front panel may be bigger or smaller than the cut-out. If the cut-out is completely enclosed by the conductor track, then the switchable area is bigger than the corresponding cut-out. If the cut-out is only partially enclosed by the conductor track, then the switchable area may be smaller than the corresponding cut-out.

Further, the switch may include a number of light source elements with different colours. The switch and/or switchable area can be illuminated by different colours.

Moreover, the switch may include a number of light source elements with the same colour. The switch and/or switchable area can be illuminated by a different brightness.

For example, the light source element may be a bulb or light emitting diode (LED).

The present invention relates also to a button panel for the control device mentioned above, wherein the button panel includes at least one cut-out, wherein the cut-out corresponds with one switch or more neighboured switches of the control device, so that the light through the button panel can pass through the cut-out out of the control device.

The object of the present invention is also achieved by a method for assembling a control device according to claim11.

The present invention relates to the method for assembling the control device, in particular for a domestic appliance, comprising at least one switch being responsive to touching a switchable area on a front side of a front panel in front of said switch by a user, said method comprises the steps of:providing at least one button panel,preparing the button panel with at least one cut-out, wherein the cut-out corresponds with one switchable area of the switch or more switchable areas of neighboured switches,applying at least one conductor track onto the button panel,providing the at least one front panel,connecting the button panel to the front panel,attaching at least one light source element at a rear side of the button panel, andattaching at least one reflector element at the rear side of the button panel and behind the light source element, so that the light can pass through the cut-out and the front panel out of the control device.

According to a first preferred embodiment of the method of the present invention for assembling a control device, the reflector element is formed as a half-shell and includes a first reflecting zone and a second reflecting zone, wherein the first reflecting zone is flat and arranged behind the at least one light source element and the second reflecting zone is concave shaped and arranged behind the cut-out. Preferably, the at least one light source element is arranged beside, below and/or above the cut-out.

According to a second preferred embodiment of the method of the present invention for assembling a control device, at least part of and preferably all of the printed icons are printed on the rear side of the front panel and/or at least one, preferably all printed non-switchable areas are printed on the rear side of the front panel. At the rear side of the front panel, the printed icons and the printed non-switchable areas are protected by the front panel against any abrasion by the user who touches the front side of the front panel for actuating a switch or for cleaning the front panel. In addition, the aesthetic appearance of the front panel is better if the printed icons and/or the printed non-switchable areas are applied on the rear side of the front panel.

In particular, the provided front panel is made of a transparent or semi-transparent material or at least that portion or those portions of the front panel arranged in front of the switch or switches, respectively, are made of a transparent or semi-transparent material.

Further, at least one of the applied conductor tracks encloses at least partially the cut-out on a front or rear side of the button panel, wherein at least one conductor track is responsive to touching the switchable area in front of the cut-out by the user.

Preferably, electric and/or electronic elements are attached on the button panel, after the at least one conductor track has been applied on the button panel.

The method is provided for assembling the control device mentioned above.

Novel and inventive features of the present invention are set forth in the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1illustrates a schematic front view of a button panel22for a control device according to the present invention. The control device is a part of a domestic appliance, for example a domestic oven. The control device is provided for adjusting relevant parameters of the appliance.

The button panel22is formed as a sheet element. In this example, the button panel22is formed as a rectangular sheet element with a rectangular recess. The button panel22includes a plurality of cut-outs12and14. Each cut-out12and14corresponds with at least one switch20.

In this example, the cut-outs12and14are arranged in series. The button panel22according to this embodiment includes six rectangular cut-outs12and five substantially square cut-outs14. The rectangular cut-out12may be provided for two corresponding switches or one tiltable switch.

The cut-outs12and14are enclosed by an inner conductor track16in each case. The inner conductor tracks16are enclosed again by a corresponding outer conductor track18in each case. Alternatively, the cut-outs12and14may be enclosed by only one conductor track. If one conductor track is provided, then the conductor track acts as transmitting and receiving antenna of the switch20. If two conductor tracks16and18are provided, then one of the conductor tracks16and18acts as transmitting antenna and the other one of the conductor tracks16and18acts as receiving antenna. In this example, the rectangular cut-outs12are enclosed by two inner conductor tracks16in each case, which are enclosed again by two corresponding outer conductor tracks18. Alternatively, the rectangular cut-outs12may be enclosed by one inner conductor track16in each case, which are enclosed again by one corresponding outer conductor track18. The square cut-outs14are enclosed by one inner conductor track16and one outer conductor track18. In each case, the conductor tracks16and18are used as sensor for detecting a human finger.

The button panel22is made of a material, which allows an arrangement of electric and/or electronic components on said front panel10. Thus, the button panel22may be also provided as a printed circuit board. Preferably, the button panel22is made of a non-transparent material.

FIG. 2illustrates a schematic rear view of the button panel22for the control device according to the present invention.

The button panel22includes the six rectangular cut-outs12and the five substantially square cut-outs14. A number of light source elements24is arranged at the rear side of the button panel22. In this example, each cut-out12and14corresponds with two light source elements24. The light source elements24for the rectangular cut-outs12are arranged beside the corresponding cut-out12in each case. The two light source elements24for one rectangular cut-out12are arranged one upon the other. The light source elements24for the substantially square cut-outs14are arranged below the corresponding cut-out14in each case. The two light source elements24for one substantially square cut-out14are arranged side-by-side. Further, a plug32is arranged at the rear side of the button panel22. The plug32is provided for connections to other parts of the appliance.

FIG. 3illustrates a schematic cross sectional side view of the control device according to a first preferred embodiment of the present invention. The cross sectional side view relates to a position, in which a switch20is arranged on the front panel10. The front panel10is arranged vertically. The switch20is arranged at the rear side of said front panel10.

For example, the switch20may be of a capacitive type, an inductive type, an optical type, an infrared type or a funk type. The switch20comprises a portion of the button panel22, the number of light source elements24and a reflector element26. The switch20comprises the corresponding cut-out12of the button panel22and that part of the button panel22, which encloses said cut-out12.

The button panel22is formed as a sheet element. The button panel22is directly arranged at the rear side of the front panel10. The button panel22may be pressed by a supporting device, e.g. by the reflector element26, against the rear side of the front panel10. Further, the button panel22may be glued by a transparent adhesive to the rear side of the front panel10. The plane of the button panel22extends in parallel to the plane of the front panel10. The button panel22is at least partially a printed circuit board. The button panel22includes one or more cut-outs14. The area of the cut-out14is equal as or bigger than the front area of the switch20. That area of the front side of the front panel10being responsive to touching by the user defines the switchable area of the switch20.

The light source elements24are arranged at the rear side of the button panel22and beside, below and/or above the cut-out14.FIG. 2shows two light source elements24. In general, one light source element24or an arbitrary number of light source elements24may be provided for each switch20. Several light source elements24allow the generation of different colours, chromaticity and/or brightness. The colours, chromaticity and/or brightness may be changed, if the button panel22has been touched, and/or if a corresponding operation has been activated or deactivated, and/or if a parameter has been changed. For example, the light source elements24are bulbs and/or light emitting diodes. The light source elements24are located directly at the button panel22, so that no further circuit boards are required as a carrier for said light source elements24.

The reflector element26is arranged behind the button panel22. The reflector element26is substantially formed as a half-shell. In this example, the reflector element26is connected to the switch20by a snap-in mechanism. In general, the reflector element26is connectable to the switch20by arbitrary means. Preferably, the reflector element26includes two different reflecting zones28and30. A first reflecting zone28forms a lower portion of the reflector element26. A second reflecting zone28forms an upper portion of the reflector element26. The first reflecting zone28is substantially flat and arranged at the same level as the light source elements24. The plane of the first reflecting zone28forms substantially an angle of about 45° in relation to the plane of the button panel22and front panel10. The second reflecting zone30is concave shaped. The light emitted by the light source elements24is reflected by the first reflecting zone28and guided to the second reflecting zone30. From the second reflecting zone30the light is reflected again to the rear side of the button panel22. The inner side of the reflector element26may be covered by a reflecting layer in order to improve the reflecting ability.

The button panel22is indirectly illuminated by the light source elements24via the reflector element26. The indirect illumination prevents “hot spots” and dark areas, and allows a homogeneous illumination of at least a part of the switchable areas.

Different switches20of the button panel22may be illuminated separately. Each switch20may either correspond with one reflector element26in each case or one reflector element26is provided for several neighboured switches20. If one reflector element26extends behind several neighboured switches20, then said reflector element26may be subdivided into separate sections by rib elements or the like. Thus, the light source elements24correspond with certain switches20.

FIG. 4aillustrates a schematic cross sectional side view of the control device according to a second preferred embodiment of the present invention.FIG. 4billustrates schematically in further detail only the front panel10that is shown inFIG. 4a. The button panel22and its details are not shown inFIG. 4b. However,FIG. 4bshows in addition a printed icon39and two printed non-switchable areas40which are arranged on both sides next to the printed icon39. The printed icon39and the two printed non-switchable areas40are formed on the rear side of the front panel10that faces towards the button panel22. The printed icon39shown inFIG. 4bis provided essentially in correspondence with the rectangular cutout12in the button panel22that is shown inFIG. 4aand that corresponds to a switch20. The printed icon39is suitably aligned with the rectangular cut-out14in order to be illuminated by the light source elements24to shine through the front panel10in order to be indicative of the corresponding switch20on the frontal side of the front panel10. The front panel10consists of a material that has a suitably chosen transparency that is adapted to the strength of the light source elements24and the printed icon39in order to allow said visible indication of the switch. The printed icon can preferably in addition have a suitable design that is indicative of the functionality of the corresponding switch.

The two printed non-switchable areas40that are shown inFIG. 4bare provided on the rear side of the front panel10on either side next to the printed icon39. Thus, the two printed non-switchable areas40are arranged on the rear side of the front panel10essentially in correspondence to regions of the button panel22, that is shown inFIG. 4a, that lie outside of the cut-out12. In that way the front panel10that consists of a transparent or semi-transparent material can be masked on its rear side in order to allow the light that is emitted from the light source elements24to shine through the front panel only in correspondence of the cut-outs12and hence of the corresponding switches.

The two printed non-switchable areas40that are shown in the right half ofFIG. 4are provided on the rear side of the front panel10on either side next to the printed icon39. Thus, the two printed non-switchable areas40are arranged on the rear side of the front panel10essentially in correspondence to regions of the button panel22, that is shown in the left half ofFIG. 4, that lie outside of the cut-out12. In that way the front panel10that consists of a transparent or semi-transparent material can be masked on its rear side in order to allow the light that is emitted from the light source elements24to shine through the front panel only in correspondence of the cut-outs12and hence of the corresponding switches.

FIG. 5illustrates a schematic cross sectional side view of a preferred variant of the button panel22of the present invention. The button panel22of the preferred variant is additionally provided with a rear gluing tape36, a filter panel34and a front gluing tape38.

The filter panel34is an optional component of the button panel22. For example, the filter panel34is a colour filter or a light diffusing foil. The rear gluing tape36connects the filter panel34to the button panel22. The front gluing tape38connects the filter panel34to the front panel22. Instead of the filter panel34, a translucent printing may be applied on the illuminated area of the front panel10. The conductor tracks16and18are in the shown example arranged between the button panel22and the rear gluing tape36.

The cut-outs12and14in the button panel22allow the use of a non-transparent material for said button panel22. Thus, the material of the button panel22has no influence to the illumination of the switches20. The material for the button panel22may be selected independently of its optical properties. This reduces the costs of the control device. In particular, the button panel22may be also used as a printed circuit board carrying electric and/or electronic elements of the control device.

The cut-outs12and14as well as the conductor tracks16and18are provided during the production of the button panel22. For example, the cut-outs12and14and the proper button panel22are prepared by one step, wherein the conductor tracks16and18are applied afterwards. The button panel22is produced in the same way and similar as a printed circuit board. Further, the button panel22may be a double-sided printed circuit board. For example, the button panel10is made of FR4, CEM1, CEM3 or the like material. Then, electric and/or electronic elements are fixed on the button panel10. Next, the light source elements24and the reflector elements26are applied to the button panel22. At last, the button panel10is glued or pressed onto the front panel10.

The conductor tracks16and18are the sensitive elements of the touch switch. The conductor tracks16and18may act a transmitting and/or receiving antenna of the touch switch20. In the latter case only one conductor track16or18may be necessary. If both conductor tracks16and18are provided, then one conductor tracks16or18acts as transmitting antenna and the other conductor track18or16acts as receiving antenna. The conductor tracks16and18form the sensitive part of the capacitive or inductive switch. Two conductor tracks16and18form the touch sensor or proximity sensor. An electric or electromagnetic field is sent and received by the conductor tracks16and18. The physical properties of said electric or electromagnetic field are changed by touching the switchable area by the human finger. A circuit for evaluating the signals on the conductor tracks16and18may be arranged on the button panel22or on another circuit board connected to said button panel22via the plug32.

FIG. 6aillustrates a schematic cross sectional side view of the button panel according to the variant shown inFIG. 5.FIG. 6billustrates schematically the front panel10according to the second embodiment of the control device of the invention that is not shown inFIG. 4. The front panel10can be fixed to the shown variant of the button panel22via the front gluing tape38on the external face of filter panel34that carries the rear gluing tape36that connects the filter panel34to the button panel22.FIG. 6bshows a printed icon39and two printed non-switchable areas40which are arranged on both sides next to the printed icon39. The printed icon39and the two printed non-switchable areas40are formed on the rear side of the front panel10that faces towards the filter panel and the button panel22. The printed icon39shown inFIG. 6bis provided essentially in correspondence with the rectangular cut-out12in the button panel22that is shown inFIG. 6aand that corresponds to a switch20. The printed icon39is suitably aligned with the rectangular cut-out14in order to be illuminated by the light source elements24to shine through the front panel10in order to be indicative of the corresponding switch20on the frontal side of the front panel10. The front panel10consists of a material that has a suitably chosen transparency that is adapted to the strength of the light source elements24and the printed icon39in order to allow said visible indication of the switch. The printed icon can preferably in addition have a suitable design that is indicative of the functionality of the corresponding switch.

The two printed non-switchable areas40that are shown inFIG. 6bare provided on the rear side of the front panel10on either side next to the printed icon39. Thus, the two printed non-switchable areas40are arranged on the rear side of the front panel10essentially in correspondence to regions of the button panel22, that is shown inFIG. 6a, that lie outside of the cut-out12. In that way the front panel10that consists of a transparent or semi-transparent material can be masked on its rear side in order to allow the light that is emitted from the light source elements24to shine through the front panel only in correspondence of the cut-outs12and hence of the corresponding switches.

Although an illustrative embodiment of the present invention has been described herein with reference to the accompanying drawings, it is to be understood that the present invention is not limited to that precise embodiment, and that various other changes and modifications may be affected therein by one skilled in the art without departing from the scope or spirit of the invention. All such changes and modifications are intended to be included within the scope of the invention as defined by the appended claims.

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