Patent Description:
It is known from <CIT> to provide an operating device for a hob with two component carriers being arranged in parallel with some distance between them. A top component carrier is a sensor component carrier with a plurality of capacitive sensor elements affixed to it. They can be pressed against the underside of a hob plate, alternatively against the backside of an operating panel of any given electrical domestic appliance. The sensor component carrier is held by a holding device, which again is mounted to the other component carrier, wherein this other component carrier is a basic component carrier with electrical components on it. This basic component carrier again is mounted to an operating housing, in which operating housing the operating device is arranged.

It is known from <CIT> to provide an MEMS package in the form of a flex circuit interconnect sub-assembly. A flex circuit is held on a carrier in the manner as in a frame, where the frame surrounds the flex circuit and does also fully cover the outer edge region on both sides for securely holding the flex circuit.

Another form of providing a printed circuit board with passive devices to be provided as single parts is known from <CIT>. The circuit board may be provided with thin film filter devices, wherein a silicon substrate may be used as a basis.

An operating device for a hob is known from <CIT>. The operating device has capacitive sensor elements and a display. The capacitive sensor elements shall be pressed against an underside of a hob plate for being operated from above by applying a finger to the hob plate.

It is an object of the invention at hand to provide an operating device for an electrical domestic appliance as well as such an electrical domestic appliance, with which problems in the prior art can be solved or avoided, and with which it is possible to hold a sensor component carrier in simple and practical manner as well as to provide a simple construction and practical manufacture.

This object is achieved by an operating device with the features of claim <NUM> as well as an electrical domestic or household appliance having such an operating device with the features of claim <NUM>. Advantageous and preferred embodiments of the invention are the subject-matter of the sub-claims and are explained in detail hereinafter.

The operating device which can be used or inserted into an electrical domestic or household appliance has a flat and planar sensor component carrier, wherein this sensor component carrier has a front side and a rear side. At least one capacitive sensor element is arranged on the front side, preferably between five and twenty capacitive sensor elements. They may be applied to the front side as a coating with a thickness of <NUM> to <NUM>, for example as metallic fields made of copper as is conventional for printed circuit boards. The operating device has a further basic component carrier with electrical circuit components thereon, for example discrete components, resistors, capacitors, relays and/or microcontrollers. A holding device is provided which may be mounted to the basic component carrier, preferably in fixed manner. The holding device is provided for the sensor component carrier and serves to hold this sensor component carrier in a predefined position, in particular behind an operating panel of an electrical domestic appliance.

According to the invention, the sensor component carrier has a planar extension or is a flat plate or board, respectively, with an extension direction and end edges. This extension direction runs from one said end edge to the other end edge, with the consequence that the end edges extend transversely to the extension direction. Preferably, the end edges are parallel to each other, such that even more preferably the sensor component carrier is basically in a rectangular shape with a specific length and a specific width. Furthermore, the sensor component carrier is narrower along the direction of extension at its front side than at its rear side in such a way that the rear side projects beyond the front side at or along both end edges in a projection or view from above onto the sensor component carrier. This means that the rear side is longer or wider than the front side. In one simple embodiment, parallel and opposite end edges are at an oblique angle to the plane of the rear side, such that the cross-section of the sensor component carrier is a trapezoid.

This specific shape of the sensor component carrier allows for various options, one of them making it easier to hold the sensor component carrier at its end edges or the outermost edges of the end edges with a holding device such that the holding device does not protrude over the front side of the sensor component carrier. Another advantage of the invention is the option to hold the end edges of the sensor component carrier in safe and defined manner.

In one embodiment of the invention, the sensor component carrier is elongated with a length that is at least <NUM>% greater than its width, preferably being at least double or triple its width. The direction of extension is perpendicular to the longitudinal direction of the sensor component carrier or its length, respectively. Furthermore, this afore-said direction of extension is the width direction and defines the width of the sensor component carrier. In this way, the width at the rear side of the sensor component carrier is greater or longer, respectively, than the width at the front side of the sensor component carrier. This can also serve to achieve the trapezoid cross-section mentioned before, which may for example have the edges with an oblique angle.

In a further embodiment of the invention, the rear side along the direction of extension is wider than the front side by a total of <NUM> to <NUM> or <NUM>% to <NUM>% of the thickness of the sensor component carrier, respectively. This means that in preferable thicknesses of the sensor component carrier being between <NUM> up to <NUM>, the sensor component carrier is rather thin with a length and a width being significantly more. The difference between the width at the front side and the width at the rear side can be about the thickness of the sensor component carrier. In one specific embodiment, this could lead to the end edges being at an oblique angle of about <NUM>° to the rear side.

According to a further aspect of the invention, the end edges of the sensor component carrier can either be continuous or straight or along a straight line, respectively. Alternatively, the end edges can be interrupted such as toothed or alike, which may in some embodiments allow for an easier mounting of the sensor component carrier in a holding device for it. Even in such an embodiment with interrupted end edges, their basic extension should be along a straight line to facilitate manufacturing and assembly.

In a preferred embodiment of the invention, the two juxtaposed end edges are designed in the same manner, in particular continuous and uniform along their length. In particular, they may have a constant profile in each case. A preferable option is to design the two end edges as mirrored to one another. This allows for example for the two end edges being juxtaposed to be straight and/or parallel to one another.

In one optional embodiment of the invention, an end edge has an end edge face running between the rear side and the front side or from the rear side to the front side, respectively. This end edge face is formed continuously along the end edge such that the sensor component carrier has a constant cross-section. In this way it is possible for the end edge face to form a constant end edge angle to the rear side. Such an angle may be between <NUM>° and <NUM>°, preferably between <NUM>° and <NUM>°.

In an alternative embodiment of the invention, such an end edge face running from the rear side to the front side is formed in a non-continuous manner. For example, the end edge face may be formed in stepped manner with at least one step, possibly with two steps, between the rear side and the front side. It is possible for one step adjoining the rear side to be less high than half a thickness of the sensor component carrier. This may provide for the lowest step of the end edge contour to be lower than half the thickness of the sensor component carrier, which again allows for an easy and reliable mounting of the sensor component carrier to a holding device for its use in the appliance.

In the invention, the holding device extends essentially on or below the rear side of the sensor component carrier, although it holds the carrier along the two end edges. For this, the holding device has holding projections such that it partially overlaps the end edges or the end edge faces, respectively, of the sensor component carrier on opposite sides of said carrier by using at least one of the holding projections. In this way, the holding device with the holding projections holds the sensor component carrier positively in the direction perpendicular to its surface. Furthermore, the sensor component carrier can be held in a steady and parallel manner to the basic component carrier. In the invention, the holding device does not completely overlap the end edges or the end edge faces as far as the front side. Even more preferably, the holding device and the holding projections are somewhat below the front side or the plane of the front side, for example by at least <NUM>% up to <NUM>% of the thickness of the sensor component carrier.

This means that in the invention, the front side of the sensor component carrier is higher in a direction from the basic component carrier to the sensor component carrier than any part of the holding device including the holding projections. Furthermore, the holding device does not completely overlap the end edges or the end edge faces up to the front side, which can particularly easily be achieved by the specific form of the end edges. This means that the outermost and lowest part of the end edges are held by the holding projections and are therefore overlapped by the holding projections, but not the complete end edges or end edge faces, respectively. This means that with regard to an operating panel of an electrical domestic appliance behind which the operating device is arranged, is touched or contacted only by the sensor component carrier or the capacitive sensor elements arranged on its front side. All the other parts of the operating device do have some distance to the back side of this operating panel, even the holding device, even if this distance may be as small as less than <NUM>, for example <NUM> to <NUM>. In a further preferred embodiment, the holding projections may form the highest parts or highest areas of the holding device such that no other part or area of the holding device is higher than these holding projections. The holding projections are needed to reach over the outest part of the end edges to hold the sensor component carrier.

In a further embodiment of the invention, the holding projections are formed exactly complementary to the end edges or end edge faces of the sensor component carrier in a region of the projections, which point towards the end edges or end edge faces, respectively. The holding projections may even rest on these end edges or end edge faces for a good and reliable holding function. This may also serve for the purpose of the holding projections not running any risk of being damaged or damaging the end edges.

In an embodiment of the invention, the sensor component carrier is seated firmly in the holding device without screws or the like. In particular, the sensor component carrier is secured against movement, in particular in a direction along the end edges, by means of a latching connection or by means of a clamp, alternatively by abutting against a stop. These should most preferably be arranged near or at one end of the sensor component carrier. Such latching connections or clamps may work together with an abutment for the sensor component carrier at opposite ends of the carrier.

In a preferred manner, the front side of the sensor component carrier with the capacitive sensor elements being formed on it are or form the highest region or part of the operating device in a direction perpendicular to its surface. This is also the direction towards the operating panel of the domestic appliance mentioned before. These capacitive sensor elements should also protrude at least <NUM>% of the thickness of the sensor component carrier above the holding device or the holding projections, respectively.

In a further preferred embodiment, the capacitive sensor elements may be formed by a metallic or electrically conductive coating on the sensor component carrier. This may be a metallic coating with copper, potentially covered with a very thin layer of tin as is known from conventional PCB. Alternatively, the capacitive sensor elements may be formed with graphite or carbon for example.

In an even further preferred embodiment, the sensor component carrier is a conventional printed circuit board with coatings in the form of tracks or surfaces or areas, respectively, on the front side and/or on the rear side. The capacitive sensor elements may preferably be in the form of surfaces, whereas these surfaces may be completely covered by electrically conductive material or in the form of a net or mesh, respectively. Such printed circuit boards are in particular according to FR4 or FR5 standard. They may also have vias or through-platings for an electrical contact from the front side to the rear side, preferably from the capacitive sensor elements on the front side to conductor tracks and/or contact fields on the rear side. This allows for an easy electrical contact to each of the capacitive sensor elements without the need of metallic contact springs, wires or the like. The vias or through-platings through the sensor component carrier should be very close or even within the capacitive sensor elements such that they produce no additional potential area for disturbing the electrical contacting of the sensor elements. The basic component carrier underneath the sensor component carrier can be provided with elastic or shape-changing and electrically conductive bodies, alternatively with springs or deformable, electrically conductive bodies or springs. They may be pressed from beneath against these contact fields on the rear side of the sensor component carrier. They are also connected to any circuits or microcontrollers on the basic component carrier as mentioned before. In a preferred embodiment of the invention, the sensor component carrier does not have any separate or discrete electrical components, not even SMD components. It should preferably be provided only with the capacitive sensor elements on the front side and contact fields or conductor tracks on the rear side.

In a further embodiment of the invention, the operating device has a display device, which preferably is an LC display or an LED display. The display device may be arranged next to the sensor component carrier with a lateral distance of <NUM> or <NUM> up to at least <NUM>. The display device has a front side which preferably runs in a parallel plane to the sensor component carrier. It is even more preferred for the display device to not project beyond or above the plane of the front side of the sensor component carrier for the same reasons as described above. The display device may also be held by the holding device or be affixed to it, respectively. This is but by other means than for the sensor component carrier.

In a preferred embodiment, the sensor component carrier has a long and rectangular form with a length along its end edges being two times up to five times its width. The number of capacitive sensor elements provided on the front side may vary between one and ten or even twenty.

The electrical domestic or household appliance according to the invention has an operating device as described before. The appliance has an operating panel behind which the operating device is arranged, for example an at least partly transparent glass panel or plastic panel. The operating device is affixed to the rear side of the operating panel or pressed against it with at least the front side of the sensor component carrier or only with its capacitive sensor elements, respectively. The display device mentioned before may also be provided on the operating device and behind the operating panel, which for this purpose should be transparent or at least partly light transmissive. The front side of the sensor component carrier should be parallel to the operating panel. On the front side of the operating panel, prints in the form of symbols, figures or letters may be provided to indicate for an operator where a specific function may be executed by touch switches comprising the capacitive sensor elements.

The basic component carrier may be affixed to a housing or the like, preferably in rigid manner. This housing may then preferably be affixed in the appliance or to the rear side of its operating panel, respectively.

In <FIG>, an oblique view of an operating device <NUM> according to the invention is shown. The operating device <NUM> has a housing <NUM>, preferably made of plastic, with a front frame <NUM> and side flanges <NUM>. The operating device <NUM> may be mounted to the rear side of an operating panel of a domestic appliance, which is shown in <FIG> later on. It may be affixed to any carrier structure or the like in the appliance, for example with a latching, which can be seen being arranged in the side flange <NUM>.

On the front face of the operating device <NUM> and within the front frame <NUM>, an LC-display <NUM> is provided together with a sensor array <NUM> made up of six capacitive sensor elements <NUM>. The capacitive sensor elements <NUM> are rectangular and of identical shape and regular arrangement. The capacitive sensor elements <NUM> are provided on a front side <NUM> of a sensor PCB <NUM>. Sensor PCB <NUM> preferably is an ordinary PCB, and a preferred manner for providing the capacitive sensor elements <NUM> includes coating with electrical conductive material. This may either be a copper plating, preferably with a thin coating of tin. Such is known in the fabrication of PCB's. Alternatively, the electrical conductive coating could be made up of material containing carbon or graphite, respectively. Another fabrication method is screen printing or spraying or the like. The capacitive sensor elements <NUM> are electrically connected to the inside of the operating device <NUM>, which will be explained later on. The basic function of the operating device <NUM> with displaying function via the LC-display <NUM> and operating elements as touch switches including capacitive sensor elements <NUM> is known in the art.

<FIG> shows a cross-section of a small part of a baking oven BO having an operating panel OP, the operating device <NUM> being pressed against the backside of the operating panel OP. The housing <NUM> is fixed in a fixture F. Operating panel OP is transparent at least in the region of the LC-display <NUM> to be visible from the outside. Above the capacitive sensor elements <NUM> it is preferably not transparent, but symbols or icons may be printed to its front side indicating the place for a user to put a finger on for effecting touch operation as indicated. This is also well-known in the art.

As will be shown further in detail later on, it can be seen in <FIG> that a front side <NUM> of the sensor PCB <NUM> is the highest part of the operating device <NUM> such that at least or, preferably, only the front side <NUM> of the sensor PCB <NUM> abuts against the backside of the operating panel OP. To be exact, not the front side <NUM> itself is abutted against the backside of the operating panel OP, but the six capacitive sensor elements <NUM> are in direct contact with the backside of the operating panel. Preferably only the capacitive sensor elements <NUM> are in direct contact with the backside of the operating panel. This is detailed later on.

As can be taken from the oblique view of <FIG> corresponding to <FIG> without the housing <NUM>, a holding device <NUM> for the sensor PCB <NUM> is provided, preferably made of plastic. The holding device <NUM> also carries the LC-display <NUM>, which is affixed to it somehow. The holding device <NUM> again is mounted onto a basic PCB <NUM> of the operating device <NUM>. This basic PCB <NUM> carries various electrical components <NUM> on its upper side, which are visible here. Further electrical components, in particular of larger size, may be provided on its underside. The LC-display <NUM> is also electrically connected to the basic PCB <NUM>, as are the capacitive sensor elements <NUM> of the sensor PCB <NUM>. This will be explained in detail later on.

<FIG> shows the holding device <NUM> without the LC-display <NUM> and without the basic PCB <NUM>. Holding device <NUM> has a number of holding projections 28a and 28b, which are forming a kind of channel between them. The sensor PCB <NUM> is inserted into this channel and firmly held by the holding projections 28a and 28b.

<FIG> shows an enlarged view onto the sensor PCB <NUM> of <FIG>. Sensor PCB <NUM> has a specific cross-section with edge faces 26a and 26b along edges 25a and 25b. This specific cross-section can also be taken from the enlarged view of <FIG>. The edge faces 26a and 26b are at an angle of about <NUM>° to the rear side <NUM> as well as to the front side <NUM>, which sides <NUM> and <NUM> are parallel to each other. This means that the above-mentioned direction of extension is from one edge 25a to the other edge 25b, which is transverse to its length. In case the sensor PCB <NUM> has a thickness of about <NUM> to <NUM>, the width at the front side <NUM> is slightly less than the width at the rear side <NUM> minus about <NUM> times the thickness. This is due to the edges 25a and 25b being ground somewhat at the transition to the rear side <NUM>. This has the reason that due to the usual material of a PCB, which is glass fiber reinforced resin, and which might brake if it is too thin, too sharp edges might break in random manner. Such should be avoided, if possible. So, in the case shown here, the difference between the width at the front side <NUM> and the width at the rear side <NUM> is about <NUM>% of the thickness of the sensor PCB <NUM> or, in other words, <NUM>% of the maximum width of the sensor PCB <NUM> at the rear side <NUM>.

The specific design of the edges 25a and 25b and the oblique edge faces 26a and 26b, respectively, allows for holding projections 28a and 28b of the holding device <NUM> to securely overlap a part of these edge faces 26a and 26b. But at the same time they are staying well back behind the plane of the front side <NUM>. This serves to achieve a positive mechanical engagement or positive locking, respectively, of the sensor PCB <NUM> at the holding device <NUM> without holding projections 28a and 28b overlapping onto the front side <NUM>. This would be necessary if the width of the front side <NUM> and of the rear side <NUM> would be identical with a conventional pure rectangular cross-section of the sensor PCB <NUM>. It can be taken from <FIG> that it is sufficient for the holding projections 28a and 28b to be only <NUM> or <NUM> below the front side <NUM>.

Not only is the front side <NUM> of sensor PCB <NUM> the highest portion or part of the operating device <NUM>, but the capacitive sensor element <NUM> is even slightly higher due to its own thickness. The capacitive sensor element <NUM> may be made up of copper with a thin tin coating, the copper having a thickness of about <NUM> to <NUM>. As can be taken later on from the enlarged view of <FIG>, this is sufficient to make sure that at least or only the capacitive sensor elements <NUM> abut against the backside of the operating panel OP, which in <FIG> is shown in dashed line.

<FIG> also shows an electrical contact to the capacitive sensor element <NUM>. For this, a hole is provided in the sensor PCB <NUM> with a through-plating <NUM> from the front side <NUM> to the rear side <NUM>. This through-plating <NUM> is connected on the front side <NUM> to the capacitive sensor element <NUM>. On the rear side <NUM>, it is connected to a contact field <NUM>, which preferably is made up in a similar manner as the capacitive sensor element <NUM>. It can be connected via an electrically conductive contact body <NUM>, which again can be connected to another similar contact field provided on the basic PCB <NUM>. The electrically conductive contact body <NUM> can be made of electrically conductive foam as is known from <CIT> cited in the beginning. As can be taken from <FIG> and <FIG>, a channel <NUM> provided in the holding device <NUM> underneath the leftmost sensor element <NUM> can receive such a contact body <NUM> and hold it in place, or the contact bodies coud be placed in the latticed structure. As an alternative, a contact body being made up of a number of electrically conductive strips being separated by isolating strips coud be provided in channel <NUM> connecting to contact fields <NUM>. As a further alternative, metal springs or the like could be provided.

<FIG> shows an alternative embodiment of a sensor PCB <NUM> with a capacitive sensor element <NUM> provided on its front side <NUM>. Edges 125a and 125b are provided between the front side <NUM> and a rear side <NUM>, wherein these edges or their edge faces 126a and 126b, respectively, may each be formed with a step or in stepped manner, respectively. This results in the edge faces 126a and 126b not being at a constant and oblique angle as shown in the example of <FIG>, but being formed in a stepped manner. This may be somewhat more difficult to manufacture compared to the oblique edge faces of <FIG>. At the same time, the result is the same and holding projections 128a and 128b, which are correspondingly formed, can firmly hold the sensor PCB <NUM> on the holding device <NUM>. As can be taken from <FIG>, this also results in a positive mechanical engagement. The manufacturing of such a PCB <NUM> may take more effort than the one of <FIG>, but the sensor PCB <NUM> can be held even more exact than according to <FIG>.

A combination of oblique and stepped edge faces can be provided. Also in the cases of <FIG>, the edge faces 26a and 26b and 126a and 126b, respectively, are the same and one is mirrored after the other. It is also an option to vary the angles of the edge faces, or to provide one edge phase in oblique manner and the other in stepped manner.

<FIG> shows the configuration of <FIG> without the sensor PCB. A reception channel <NUM> for inserting the sensor PCB <NUM> is formed by the holding projections 28a and 28b. Its underside is formed by a kind of grate forming the channels <NUM> for the above described contact bodies to reach through the holding device <NUM> down to the basic PCB <NUM>. <FIG> clearly shows that the sensor PCB <NUM> can easily be inserted into the reception channel <NUM> and completely moved or pushed in, respectively, to reach the right end of the reception channel <NUM>. This can be taken from <FIG>, for example. If the holding projections 28a and 28b are pressed with slight force against the edge faces 26a and 26b, which does not pose a problem for inserting the sensor PCB <NUM>, the holding force for this sensor PCB <NUM> at the holding device <NUM> is fully sufficient. A latching mechanism or the like could be provided for on the sensor PCB <NUM> and/or the holding device <NUM>, respectively. Alternatively, the front frame <NUM> of the housing <NUM> which is moved over the basic PCB <NUM> and a part of the holding device <NUM> may abut at the left end of the sensor PCB <NUM> which is protruding slightly over the left side of the holding device <NUM>, which for example can be taken from <FIG>. In this manner, in the mounted state of the operating device <NUM> according to <FIG>, the sensor PCB <NUM> is firmly secured in place and cannot be moved out of the channel <NUM>.

Claim 1:
Operating device (<NUM>) for an electrical domestic appliance (BO), the operating device (<NUM>) having:
- a flat and planar sensor component carrier (<NUM>, <NUM>) with a front side (<NUM>, <NUM>) and a rear side (<NUM>, <NUM>), wherein at least one capacitive sensor element (<NUM>, <NUM>) is arranged on the front side (<NUM>, <NUM>),
- a further basic component carrier (<NUM>) with electrical circuit components (<NUM>) thereon,
- a holding device (<NUM>, <NUM>) for the sensor component carrier (<NUM>, <NUM>) being mounted to the basic component carrier (<NUM>),
wherein
- the sensor component carrier (<NUM>, <NUM>) has a planar extension with one extension direction and end edges (<NUM>, <NUM>), wherein the extension direction runs from one end edge (<NUM>, <NUM>) to the other end edge (<NUM>, <NUM>) such that the end edges (<NUM>, <NUM>) extend transversely to the extension direction,
- the sensor component carrier (<NUM>, <NUM>) is narrower along the direction of extension at the front side (<NUM>, <NUM>) than at the rear side (<NUM>, <NUM>) in such a way that the rear side (<NUM>, <NUM>) projects beyond the front side (<NUM>, <NUM>) at both end edges (<NUM>, <NUM>) in the projection onto the sensor component carrier (<NUM>, <NUM>),
- the holding device (<NUM>, <NUM>) extends essentially on or below the rear side (<NUM>, <NUM>) of the sensor component carrier (<NUM>, <NUM>) and has holding projections (<NUM>, <NUM>),
- the holding device (<NUM>, <NUM>) partially overlaps the end edges (<NUM>, <NUM>) or the end edge faces (<NUM>, <NUM>) of the sensor component carrier (<NUM>, <NUM>) on opposite sides of the sensor component carrier (<NUM>, <NUM>) with in each case at least one of the holding projections (<NUM>, <NUM>) and holds the sensor component carrier (<NUM>, <NUM>) positively in the direction perpendicular to its surface,
characterized in that
- the holding device (<NUM>, <NUM>) does not completely overlap the end edges (<NUM>, <NUM>) or the end edge faces (<NUM>, <NUM>) as far as the front side (<NUM>, <NUM>),
- the front side (<NUM>, <NUM>) of the sensor component carrier (<NUM>, <NUM>) is higher in a direction from the basic component carrier (<NUM>) to the sensor component carrier (<NUM>, <NUM>) than any part of the holding device (<NUM>, <NUM>) including the holding projections (<NUM>, <NUM>).