WO2005043760A1

WO2005043760A1 - Control device for controlling an electrical appliance with a touch-sensitive switch

Info

Publication number: WO2005043760A1
Application number: PCT/EP2004/012399
Authority: WO
Inventors: Ewald Bayer
Original assignee: E.G.O. Control Systems Gmbh
Priority date: 2003-11-03
Filing date: 2004-11-03
Publication date: 2005-05-12
Also published as: DE10352681A1

Abstract

In one embodiment, invention concerns a control device (11), such as a clothes dryer, comprising a touch-sensitive switch provided with a sensing element (17) consisting of a body made of foam having a suitable shape. The latter is supported on a contact surface (13) and enables a capacitive coupling, for example when a user presses his finger (15) on said contact surface. The sensing element (17) is supported on a circuit card (21) and has a central longitudinal channel (18), wherein a light emitting diode (23) is placed on the circuit card. To prevent the occurrence of electrical interference, a gap is maintained between the sensing element (17), the light emitting diode (23) and the power supply cables (24). Therefor, the sensing element is placed spaced apart from the other electrical devices or has suitable recesses in the zone where it would be too close to the other electrical devices.

Description

Description Operating device for operating an electrical device with a touch switch

Field of application and state of the art

The invention relates to an operating device for operating an electrical appliance, which can be, for example, a household appliance such as a clothes dryer, according to the preamble of claim 1.

Operating devices or so-called touch or touch switches are known for example from EP 859 467 A1. These usually work well, but have the problem with a compact design that they can have a certain susceptibility to failure. Above all, this limits the freedom of design, particularly with regard to the electrical controls. For example, it is known from the aforementioned EP 859 467 A1 to provide the body of the sensor element with a continuous opening in which an LED is attached. This can radiate upwards through a cover or front panel, in particular a glass ceramic cover or made of plastic, to identify the sensor element or the contact point formed thereby. However, the problem that the activation of the LED interferes with the evaluation of the sensor element often arises here.

A similar operating device is known from EP 1 257 057 A1. Here too, lighting is provided below a contact surface, among other things, as a marking of the contact surface.

From EP 1 030 536 A1 it is known to provide a capacitive touch switch for an operating device for a hob nearby or above a display. From DE 3119495 A1 it is known to apply a thin foam layer as a sensor for a capacitive proximity switch on an elevated angled support. The foam layer serves to adapt to the underside of a cover.

Task and solution

The invention has for its object to provide an operating device mentioned at the beginning with which the problems of the prior art can be avoided and in particular an operating device or an arrangement of a sensor element can be created which ensures interference immunity in the case of various arrangement options.

This object is achieved by an operating device with the features of claim 1. Advantageous and preferred embodiments of the invention are the subject of the further claims and are explained in more detail below. The wording of the claims is made the content of the description by express reference.

According to the invention, in an operating device mentioned at the beginning, the sensor element is a flexible and electrically conductive body. It is arranged adjacent to a cover with one side, whereby in a known manner it thereby forms a surface of a capacitor, the capacitance of which can be changed by approaching or touching, which can be evaluated. The cover serves as a contact or approach surface. The sensor element is arranged or fastened to a support which can be provided with electrical conductors, in particular also for the sensor element itself. This support can in particular be a printed circuit board. The body of the sensor element has a minimum distance or signal-to-noise ratio to the electrical cables. tern or to the edition, which is usually at least one to several millimeters. This distance is intended to prevent electrical interference signals, in particular those originating from the electrical lines on the support, from being coupled into the sensor element or its body and thus from interfering with the signal of the sensor element or its evaluation. If this distance is maintained, for example LEDs can also be provided very close to or in a recess in the sensor element. For increased interference immunity, the distance, which is also referred to below as the signal-to-noise ratio, can also be 3-4 mm or more.

Due to the design as a body, the sensor element can have electrical properties, which it achieves primarily through its volume or its length in the direction of the cover. An electrical resistance is particularly worth mentioning here, which can dampen interference signals. This effect can hardly be achieved with a thin layer of such a material. The resulting electrical resistance would be too low here.

In a further embodiment of the invention it can be provided that the sensor element does not directly touch the support. The resulting distance can be, for example, the signal-to-noise ratio. This is preferably achieved by a spacer element, which is constructed, for example, like a bridge. The sensor element can be arranged or attached to this spacer element which rises above the support. The bridge or the spacer element can also be used for electrical contacting.

If the spacer element is designed as a bridge, it can have one or more arms. Several sensor elements can also be arranged next to one another on the bridge. In this case, electrical contacting to the sensor elements would have to be independent of the be formed, for example via additional connections. In the case of a multi-arm bridge, it is advantageous for the Monday if it is a one-piece component. From a support surface of the bridge, on which the sensor element essentially rests, several arms can emerge which support or form the bridge. Alternatively, although with greater effort, several bow-like, individual arms can be provided, which are arranged next to one another in such a way that they can carry a sensor element.

It is preferably provided that the bridge, on which the body of the sensor element rests, is soldered to the support. Alternatively, it can be attached to the support by an easily detachable connection, for example by a snap connection. In this way, a bridge can be mechanically snapped into place and, under certain circumstances, even released by hand without the need for tools.

The spacer is advantageously provided with an attachment or holder for the body. This can either be gluing. Alternatively, it can be attached to a mandrel or a similar projection in order to fasten the sensor element to the spacer element.

Alternatively, the body of the sensor element can at least partially rest on the support. Then either all electrical conductors or electrical components with at least the signal-to-noise ratio to the sensor element are to be provided. Furthermore, it can be provided that the sensor element has a recess or indentation at a suitable or endangered point, deviating from the other course of its geometric shape, in order to in turn establish the signal-to-noise ratio. In a preferred exemplary embodiment of the invention, the sensor element or the body, which is essentially formed from a non-woven material, has a recess in a central region. This can run as a central, continuous hole in the direction of the contact surface. While the sensor element rests with one side of the body on the underside of the cover or contact surface, a lamp is arranged at the other end. Radiated light goes through the body to the bottom of the contact surface. This should have a translucent light channel for the lighting or be translucent at this point.

Such a light channel can be, for example, an insert made of transparent or translucent material fitted into the cover. For example, it can also extend into the body or into the recess and run in the direction of the illuminant, in particular as far as the illuminant.

Furthermore, the illuminants can be arranged on the support, which in this case is advantageously a printed circuit board. The electrical leads to the illuminant can be provided on the side of the support which points towards the sensor element. In this case it is possible to provide a fastening for the sensor element on the lamp, in particular by the lamp itself. For this purpose, this can have, for example, a correspondingly large or appropriately designed housing, onto which the sensor element can simply be attached. The body of the sensor element can be tightly and mechanically firmly attached to the lamp.

As an alternative to attaching a light source directly in the sensor element, it can be provided that light can be introduced into or onto the sensor element by means of a light guide, which in principle can be configured similarly to that described above. A fundamental advantage Such a light guide is such that illuminants, which can generally disrupt the sensor element due to the electrical control, can be provided away from the sensor element. Furthermore, it is also possible to design such a light guide as a holder for the sensor element. For this purpose, it can have a corresponding widening, for example, which reaches under the sensor element. With another end, the light guide can be inserted into a corresponding opening on the cover. In this way, a translucent closure of the cover is achieved, by means of which the sensor element is simultaneously fastened to the underside of the cover in a precisely predetermined position.

The support is advantageously a printed circuit board. It can be equipped on one side, for example with SMD components. The component side advantageously faces the contact surface, as a result of which, for example, lamps such as LEDs can be used as SMD components. It can also be equipped on the underside or on both sides.

In a further embodiment of the invention, it is possible to design the body of the sensor element such that it approximately corresponds to a truncated cone. This means that it is relatively small towards the contact point in order to contact the contact surface. At the opposite end it is wide and considerably larger, the sensor element body advantageously having a constant wall thickness. This has the advantage that an LED can be arranged at this larger end as described above. The large dimensions of the body at this end ensure a sufficient distance between the sensor element and such an LED. In addition, it can be provided that even with such a sensor element body, the sensor element is cut out or cut out in the area in which, for example, the feed lines to the LED run. These and further features of preferred developments of the invention are evident from the claims and also from the description and the drawings, the individual features being implemented individually or in groups in the form of sub-combinations in one embodiment of the invention and in other fields, and can represent advantageous and protectable versions for which protection is claimed here.

Brief description of the drawings

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

1 shows a side section of a possible operating device according to the invention with a sensor element which is arranged on a bridge between the board including the LED and the contact surface, FIG. 2 shows a modification of an operating device from FIG. 1 with spacing-maintaining spacing nails for the sensor element, FIG. 3 shows a modification of an operating device with a holder for the sensor element, which is designed as a transparent plastic part which is put on the LED, FIG. 4 shows a modification of an operating device in which a frustoconical sensor element is clamped between the circuit board and the contact surface, 5 shows a top view of the sensor element from FIG. 4, FIG. 6 shows a side view of the sensor element from FIG. 4, FIG. 7 shows a top view of the bridge from FIG. 1 and FIG. 8 shows a modification of the bridge from FIG narrower support surface in an H-like shape. Detailed description of the exemplary embodiments

In Fig. 1, an operating device 11 is shown schematically, which has a cover 12 with a contact surface 13 on which a finger 15 is placed for operation, as can be seen from the broken line. A sensor element 17, which extends to the underside of the cover 12, is provided below the contact surface 13. At the other end, the sensor element 17 is placed on a bridge 19 which is fastened to a printed circuit board 21 and runs over it. The sensor element can have a height of several mm, for example 10 mm or more. In combination with the specific electrical resistance of the material, an overall resistance is achieved that can vaporise disturbances, for example.

As can be seen, the sensor element 17 has a central longitudinal channel 18 into which light is radiated upwards by an LED 23 arranged below the sensor element 17 and is radiated upwards through a translucent insert 25 in the cover 12. Such a translucent insert 25 is to be used when the cover 12 itself or in the area of the contact surface 13 is not translucent.

The design of the sensor element 17 from electrically conductive plastic or foam and its principle of operation, in particular also because of the electrical properties due to the design as a voluminous body, can be found in EP 859 467 A1, the contents of which are hereby expressly referenced to the content this description is made.

The LED 23 is provided with schematically illustrated supply lines 24, which in the case of the printed circuit board 21 which is populated on one side in this case on the to the cover 12 facing side are provided. Through the bridge 19, which is also provided with a feed line 20 for electrically contacting the sensor element 17, the sensor element is kept at a distance from the LED 23 and the feed lines 24. This distance, which is about 2 mm at the scale 1: 2 of the illustration chosen here, is the aforementioned signal-to-noise ratio. Compliance with this signal-to-noise ratio prevents the signals given to the LED 23 for display from being coupled into the sensor element 17 or their feed lines 20 via the bridge 19. In this respect, it is also important that not only the sensor element 17 itself but also its electrical contact maintains the signal-to-noise ratio to other electrical components, for example the LED 23. This can be seen from FIG. 1. There, the leads 20 to the bridge 19, via which the sensor element 17 is contacted, also go in a different direction than the leads 24 of the LED 23.

A top view of this bridge is shown in Fig. 7. It shows how the bridge 19 has an annular support surface on which the sensor element 17 is placed. Four arms protrude laterally from the annular support surface, which are bent twice and support the support surface of the bridge 19 above the printed circuit board 21.

An alternative embodiment of a bridge is shown in FIG. 8. The bridge 419 shown there has a significantly reduced contact area. In plan view, it is designed approximately like a double H such that the bearing surface is formed by part of the arms and by two crossbars connecting the arms. The LED underneath can shine through a central recess, which is approximately aligned with the longitudinal channel 18 of the sensor element 17. The material consumption of this bridge 419 is lower than that of FIG. 7. In a further embodiment of the invention, it is conceivable to dispense with the crosspieces between the long arms as long as the carrying function for the sensor element 17 can still be ensured. In this case, two individual arms, which roughly correspond to metal strips, can run parallel to one another and form a kind of bridge.

The arrangement shown in FIG. 1 makes it possible to design the LED 23 as a so-called SMD component and thus to provide the leads 24 to it on the side facing the contact surface 23. Thus, the circuit board can be equipped on one side, facing the cover 12. Alternatively, it is also conceivable to provide the leads 24 to the LED 23 or other leads to other components on the printed circuit board 21 on the side facing away from the sensor element 17 or the contact surface 13. In this case, the signal-to-noise ratio according to the invention can nevertheless be provided for the sensor element, for example by means of a bridge, in order to further increase the interference immunity.

From the modification in FIG. 2, with the same construction of the cover 12, it can be seen how the bridge 19 is replaced by so-called spacer nails 127. These can be attached to the printed circuit board 121 in the manner of solder pins or the like. The sensor element 1 17, which is similar to that in FIG. 1, is slipped onto the upper tips. The electrical contacting to the sensor element 117 can advantageously take place via the spacer nails 127, which can be made of metal for this purpose and can, for example, be soldered onto the printed circuit board 121. The circuit board 121 is equipped on both sides here, as can be seen.

In the further embodiment according to FIG. 3, a holder 229 is placed or attached to the LED 223, which is provided with leads 224 on the printed circuit board 221 in a manner similar to FIG. 1. The holding tion 229 is made of transparent material, especially clear plastic. This is illustrated by the fact that the light from the LED 223 passes through the holder 229. The bracket 229 has protruding projections or a circumferential collar 230 projecting outwards. This keeps the sensor element 217 at a distance from the LED 223 or the printed circuit board 221, similar to the bridge according to FIG. 1 or the spacing nails according to FIG. 2, as before. The fastening of the holder 229 to the LED 223 can be advantageous be such that it is self-locking and therefore stable without further connections, such as gluing or the like. In an embodiment, not shown, the holder can protrude upwards with a section that resembles insert 25 from FIG. This section could be fixed in the cover so that it fixes the holder together with the sensor element to the cover. A support on the circuit board or the LED would then no longer be necessary and the sensor element can or the like without a circuit board. be held in a defined position on the cover by means of the holder.

The electrical contact to the sensor element 217 is made by a schematically indicated supply line 231. This can be, for example, a wire that is inserted into the sensor element. It could also be a contact spring which is pressed laterally onto the sensor element.

4 shows a further embodiment of an operating device 311. On the one hand, the cover 312 has only one opening through which light emerges. Furthermore, the sensor element 317 is frustoconical in shape with an essentially constant wall thickness. The signal-to-noise ratio according to the invention is achieved here in two different ways. In the left half of the sensor element 317, the wall extends through the obliquely inclined profile from the upper contact surface 313 so far from the LED 323 and the left feed line 324 that the signal-to-noise ratio is ensured. there The left feed line 324 runs, for example, with the corresponding signal-to-noise ratio to the sensor element 217 to a connection (not shown) on the printed circuit board 321, which leads to the underside and for example leads away with a cable. This ensures that the signal-to-noise ratio is always guaranteed.

In the right area of the sensor element 317, a cutout 332 is provided in the manner of a partial perforation. Through this cutout 332, the right feed line 324 runs outward on the printed circuit board 321. The technical principle on which this is based is that the sensor element 317 essentially rests on the printed circuit board 321 and only in those areas which could come close to the LED 323 or a feed line, a corresponding cutout or recess is provided.

Through this cutout, a light guide could also reach the sensor element from the outside and go inside into the sensor element, which is not shown, similar to the transparent holder in FIG. 3. Thus, a distance between the sensor element and the lamp or Supply lines to be created. The light guide can also have a holding function for the sensor element.

5 and 6 show a top view and an uncut side view of how the cutouts 332 lead through the wall of the sensor element 317. It can be seen how the cutouts 332 are provided approximately opposite one another. However, it is also conceivable to carry them out relatively close to one another or to lead several electrical lines or feed lines through a single somewhat wider cutout.

Claims

claims

1. Operating device (11) for operating an electrical device, preferably a household appliance such as a clothes dryer, with a sensor element (17) of a proximity or touch switch, the sensor element being a flexible, electrically conductive body which is attached to a cover (12) as a contact surface The sensor element (17) is arranged on a support provided with electrical conductors (20, 24), such as a printed circuit board (21), characterized in that the body of the sensor element is a distance from the electrical conductors (24) as a signal-to-noise ratio. or is at a distance from the support (21), the distance being at least one to two millimeters.

2. Control device according to claim 1, characterized in that the distance is at least three millimeters, preferably at least four millimeters.

3. Control device according to claim 1 or 2, characterized in that the sensor element (17) does not directly touch the support (21).

4. Control device according to claim 3, characterized in that a spacer element (19, 127, 229, 419), preferably a bridge (19, 419), is arranged on the support, on which the sensor element (17) is several millimeters apart the support (21) is arranged or fastened, with fastening being provided in particular on the spacer element towards the sensor element, preferably gluing or mechanical attachment.

5. Control device according to claim 4, characterized in that the spacer element (19, 127, 229, 419) for the signal-to-noise ratio to the electrical supply lines (24) is soldered onto the support (21), the spacer element preferably providing the electrical connection to the Sensor element (17).

6. Operating device according to claim 4 or 5, characterized in that the bridge (19, 419) has a support surface for the sensor element (17), in particular with a shape adapted to the sensor element, from which a plurality of arms extend, which rest on the support (21 ) are supported and / or attached.

7. Operating device according to one of the preceding claims, characterized in that the support is a printed circuit board (21) equipped on one side, preferably with the component side facing the contact surface (13).

8. Control device according to claim 1 or 2, characterized in that the sensor element (17) partly rests on the support (21) and in the area in which electrical conductors (24) extend or electrical components (23) are arranged on the support , the sensor element has at least one correspondingly large recess (332) for maintaining the distance.

9. Control device according to one of the preceding claims, characterized in that the sensor element (17) has the shape of a hollow truncated cone, wherein it covers a continuous surface on the side facing the contact surface (13) for contact with the underside of the contact surface (13 ).

0. Control device according to one of the preceding claims, characterized in that the sensor element (17) has a recess in a central region, preferably a bore (18) in the direction of the contact surface (13).

1 1. Operating device according to one of the preceding claims, characterized in that at the end of the body of the sensor element (17) which faces away from the contact surface (13), a lamp is arranged, in particular an LED (23), and its light radiates through the body or through a recess (18) in the body of the sensor element to the contact surface, the cover (12) preferably having a translucent light channel (25).

12. Operating device according to claim 11, characterized in that the translucent light channel (25) is an insert made of transparent material in the cover (12), wherein it preferably extends at least partially into the body and in particular up to the illuminant (23) runs there.

13. Control device according to claim 11 or 12, characterized in that the illuminants (23) on the support (21), in particular in the form of a printed circuit board, are arranged, preferably the leads (24) to the illuminant on the to the sensor element ( 17) pointing side of the support are provided.

14. Operating device according to one of claims 11 to 13, characterized in that a fastening for the body of the sensor element (17) is provided directly on the lamp (23), preferably an enlarged housing (229) of the lamp, on which the body of the Sensor element with a corresponding Appropriate recess (218) can be fastened tightly and mechanically.

15. Operating device according to one of the preceding claims, characterized in that light guides are provided which extend from a lamp arranged away from the sensor element (17) to the sensor element or into it and radiate upwards through a recess in the body to the cover ,

16. Operating device according to one of the preceding claims, characterized in that a light guide at one end has a holder for the body of the sensor element (17), in particular a widening, and at the other end can be inserted through a recess in the contact surface (13) , as light guide and attachment for the sensor element.