Patent Application
20230216498
The invention relates to an operating unit for a household appliance having a touch-sensitive unit and an LED unit positioned on the rear thereof.
A variety of operating units for household appliances are known from the prior art. In the simplest case, a household appliance is operated by pushbuttons or rotary switches, the position of which is visible from markings on a panel. The use of unlit membrane keys on microwave ovens, for example, is also known. Also known are touch-sensitive buttons grouped around a small LCD display, the current function of each of which is indicated to the user by a symbol.
EP 3 280 053 A2 discloses an operating module for a household appliance, in particular a hob. The previously known operating module has a symbol foil applied to a mounting surface of a support with at least one touch-sensitive touchpad. The at least one mounting surface has an illuminated area beneath the at least one touchpad. Each of the at least one touchpads also has a metal layer with at least one recess for forming a symbol. Furthermore, the metal layer is electrically conductively connected to an electrical connection of the character foil. One of the disadvantages is that apart from the symbol foil a further diffuser foil is needed to equalize the lighting.
One object of the invention is to specify an operating unit with a simplified structural design compared to previously known solutions and improved readability.
The aforementioned object is achieved in accordance with claim 1 in that the touch-sensitive unit is formed with a diffusor foil, the top side of which, facing an operator, is provided with a printed character layer and the underside of which, directed away therefrom, is provided with a printed functional layer. This leads to a simpler and particularly robust structure of the operating unit, which allows a significant cost reduction. Furthermore, due to the fact that essentially only one diffusor foil printed on both sides is required as the primary function component, better optical perceptibility of the operating unit results for a user, particularly under difficult external lighting conditions. The diffusor foil also serves to equalize the light emitted by the LED unit, which is equipped with a plurality of discrete light-emitting diodes.
The character layer and the functional layer of the diffusor foil are preferably formed by screen printing. As a consequence, large-scale and cost-effective manufacture of the layers by means of proven printing technology with simultaneously high repeat accuracy of the character reproduction is ensured.
In a technically advantageous embodiment, the functional layer has a plurality of capacitive touch electrodes, each of which is embodied, when a finger of the operator becomes physically close, to generate an analyzable electrical signal. As a consequence, a convenient, intuitive and ergonomic touch functionality of the operating unit can be realized. Moreover, in the functional layer a plurality of conductor tracks are formed, which serve for electrical connection of the individual capacitive touch electrodes to a central electrical connection zone of the operating unit, which can for example be constructed in the form of a multipole connector. Under normal conditions, when a finger approaches to within less than 5 mm, the capacitive touch electrodes emit an analyzable electrical signal.
Preferably the electrical signals from the capacitive touch electrodes can be conducted, via a printed conductor track assigned to each of these, to at least one electrical connection zone of the functional layer. In this way, the operating unit can be easily and flexibly electrically connected with a control and/or regulating unit of a household appliance. A side-extending, strip-like section of the diffusor foil can function here at the same time as a flexible printed circuit board (FPC). At at least one free end of the strip-like section a reinforcement with a connection zone is preferably formed, such as a multipole connector, etc.
In the case of a further embodiment, the character layer has a plurality of preferably negatively printed and at least in some areas light-permeable characters, with each capacitive touch electrode being preferably associated with a character of the character layer. Due to the congruency between the capacitive touch electrodes and the characters applied to the character layer a clear association results between a function desired, and to be triggered, by an operator or user and the touch electrode concerned.
Preferably, each character of the character layer can be individually illuminated by means of at least one light-emitting diode arranged on a printed circuit board of the LED unit. As a consequence, for example following the triggering by the user of the capacitive electrode associated with a character, the character may light up briefly or continuously as confirmation. Furthermore, the individual illumination capability of the characters allows convenient operation even under difficult lighting conditions, such as strong sunlight.
In a favorable development the printed circuit board of the LED unit has at least one numeric or alphanumeric display for illuminating a character. In this way, numbers or even complete text messages can be displayed to the user by means of the LED unit.
In a technically favorable development each light-emitting diode and each numeric or alphanumeric display of the LED unit has a light well as part of a light guide. In this way, optical crosstalk between light signals of closely adjacent light-emitting diodes or alphanumeric LED displays, as in the form of 7-segment displays, 5×7 dot-matrix displays, etc., is avoided. The light wells can have a mirrored interior surface in at least certain areas.
Preferably, the printed functional layer is covered by a protective layer at least in certain areas. In this way, the capacitive touch electrodes formed by screen printing within the functional layer and the associated electrical conductor tracks are permanently protected from harmful oxidative environmental influences, such as humidity etc., and mechanical damage. The protective layer can, for example, be realized using a protective foil or a protective lacquer.
Preferably, the diffusor foil is established in the region of a parallel section and in a connecting section is flexibly bendable and/or rotatable at least in certain areas. In this way, a spatially flexible electrical connection between the operating unit and an optional, higher-level, electronic control and/or regulating unit is possible. In a connecting section the diffusor foil is preferably reinforced by a reinforcement, to allow the insertion into an electrical connector or plug socket, or similar.
In an advantageous technical development, it is provided that the printed circuit board and the light guide are fixedly connected with the touch-sensitive unit to create the integrated operating unit. In this way, the LED unit and the touch-sensitive unit form a structurally compact, integral unit. The connection can take place by means of an adhesive layer formed at least in certain areas between the protective layer and the light guide.
Preferably the character layer is covered by a light-permeable cover. As a consequence, mechanical damage to the character layer, for example from operational wear, scratches from falling objects, bleaching solar radiation, and so on, is excluded. Furthermore, the ingress of moisture, foreign particles and similar into the operating unit is prevented. In the event of application of the operating unit in a hob, the light-permeable cover is preferably realized by the glass area for cooking utensils.
A preferred exemplary embodiment of the invention is described in more detail below with the aid of schematic figures, in which:
Beneath the touch-sensitive unit 106 is an LED unit 136, which essentially has a rigid printed circuit board PCB 138, a block-like light guide 140, and a thin, light-permeable adhesive layer 142 for the bonded connection of the LED unit 136 with the underside protective layer 134 of the functional layer 124 of the touch-sensitive unit 106. The LED unit 136 of the operating unit 100 serves primarily for backlighting the symbols or the individual characters of the character layer 120 of the diffusor foil 116.
On the printed circuit board 138 of the LED unit 136, merely by way of example here, at least one LED 150, a numeric or alphanumeric display 152, and an electrical connection zone A1, are arranged. The connection zone A1 comprises a plurality of electrical contacts, of which here just one contact A2 is graphically shown and considered representative of all others. The numeric display or alphanumeric display 152 can, for example, be realized with a 7-segment display or with a 5×7 dot-matrix display.
The adhesive layer 142, the protective layer 134, the functional layer 124, the supporting diffusor foil 116, and the cover 130 are essentially in each case fully light-permeable, with a foil-like and flexible nature. The character layer 120 is light-impermeable except for the printed symbols or characters, so that when the LED unit 150 has been activated the symbols or characters have a negative or inverted appearance to the eye 166. This means that the characters appear brightly lit in front of the character layer that is otherwise printed in black, for example.
The LED 150 and the numeric or alphanumeric display 152 emit light 158, 160 or light signals for back-lighting of characters of the character layer 120 and thereby for visualization of an operating status of the household appliance. The light 158, 160 in each case passes through an associated light well 162, 164 within the block-like light guide 140, penetrates the adhesive layer 142, the protective layer 134, the diffusor foil 116, the character layer 120 and finally the cover 130 and reaches the eye 166 of the user or operator of the household appliance equipped with the operating panel 100. Due to the parallel spacing and thus optical isolation from one another of the light wells 162, 164 crosstalk between the light 158, 160 or light signals emitted by the LED 150 and/or the 7-segment display is avoided. Furthermore, oblique irradiation of bright ambient light into the LED unit 136 and thus an outshining of the LED 150 or the numeric or alphanumeric display 152 is avoided.
In the region of the light guide 140, the touch-sensitive unit 106 and the LED unit run in a parallel portion 170 substantially parallel at a distance from one another between the plate-like transparent cover 130 and the similarly rigid printed circuit board 138 of the LED unit 150.
The parallel section 170 merges laterally into a connecting section 172 and a free adjoining section 174 which in turn adjoins this, so that the operating unit for example can be connected in a spatially flexible manner with an electronic control and/or regulating unit of the household appliance. Here, for example, the top side 118 of the diffusor foil 116 in the region of the adjoining section 174 has a plate-like reinforcement 176, wherein on the underside 132 of the functional layer 124 directed away from the reinforcement 176 a central electrical connection zone 180 is formed, which can comprise a plurality of electrical contacts, of which here only one electrical contact 182 is indicated graphically and is considered representative of all the others. In the region of the connecting section 172 the touch-sensitive unit 106 constitutes a flexible printed circuit board, while the printed circuit board 138 is of a rigid nature throughout.
By means of the flexible connecting section 172 the touch-sensitive unit 106 is electro-conductively connected to the LED unit 136 by means of the connection zone 180 and the electrical contacts A2 of the connection zone A1.
The diffusor foil 116, acting as a light distributor, of the touch-sensitive unit 106, apart from the electrical functional layer 124 for realizing the touch sensitivity, also comprises the character layer 120 with the printed characters required for operator guidance or the necessary symbols, which compared to previously known solutions allows a design which is structurally considerably simpler, easier to manufacture and ultimately more cost-effective. Furthermore, an increased optical performance of the operating unit 100 results since, due to the diffusor foil 116 with its threefold functionality (uniform light distribution, character layer and functional layer), fewer foils and adhesive layers are required, allowing a reduction in undesired optical reflections and losses and an exceptional display contrast of the operating unit 100.
At its free end, the connecting section 172 has the adjoining section 174 with the reinforcement 176 and the central electrical connection zone 180 or a connector with a plurality of electrical contacts, of which just one electrical contact is provided with reference character 182 to represent all the others.
The characters 190, 192, 194 and 196 are in each case designed to be light-permeable. For example, the symbol characters 190 can in each case be backlit by at least one LED, which is designed according to the LED 150 of
By means of the electrical connection zones 154 of the printed circuit board 138 with in each case a plurality of electrical contacts, of which in each case just one electrical contact provided with the reference character 156 is considered representative, the operating unit 100 can, for example, be electrically connected with an electronic control and/or regulating unit (not shown) or other electrical components of the household appliance.
Apart from the at least one LED 150 and the at least one numeric or alphanumeric display 152 from
The first frame-shaped capacitive touch electrode 220 is arranged in the region of the character 192 indicated by dots, representing the Arabic numeral ‘9’, with the character layer 120, which is hidden here, passing below the diffusor foil 116. Accordingly, the frame-shaped capacitive touch electrode 222 is associated with the character 192, representing the Arabic numeral ‘8’. The frame-shaped capacitive touch electrode 224 comprises the character 192 for the number ‘7’. The frame-shaped capacitive touch electrode 226 comprises the character 190, which here, for example, symbolizes an analog clock and the frame-shaped capacitive touch electrode 228 comprises the character 194 in the form of a digital clock or a timer.
With the aid of the capacitive touch electrodes 220, 222, 224, 226, 228, when the operator's finger is sufficiently close, an electronically analyzable electric signal S1, . . . , 5 can be generated in each case. Moreover, in the electrical functional layer 124 of the diffusor foil 116 or on the underside 122 of the diffusor foil 116, there pass a plurality of conductor tracks similarly produced by screen printing, of which just one conductor track 234 is drawn to be representative for all others with reference character 234.
With the aid of the conductor tracks 234, the individual electrical signals S1, . . . , 5 from the capacitive touch electrodes 220, 222, 224, 226, 228, are passed here to a respective associated electrical contact of the central electrical connection zone 180. When an operator's finger approaches one of the capacitive touch electrodes 220, 222, 224, 226 or 228 the respective electrical signal S1, . . . , 5, is generated which, by means of the electrical conductor tracks 234, is passed to the electrical connection zone 180. With the aid of the control and/or regulating unit (not shown) an action corresponding to the character associated with the respective touch electrode 220, 222, 224, 226, 228 can then be triggered.
An optical confirmation of the action selected by the operator can be provided, for example, by the backlighting of the corresponding symbol of the operating unit 100 by means of an associated LED or numeric or alphanumeric display of the LED unit. For example, upon activating the capacitive touch electrode 226 with the character 190 associated with this in the form of an analog clock, the setting of an internal clock of the household appliance can be initiated with the aid of the control and/or regulating unit.
The functioning of capacitive touch electrodes will be sufficiently familiar from the prior art to a personal skilled in the art working in electronics, such that their detailed functioning requires no further explanation at this point for reasons of succinctness and brevity.
The operating unit 100 according to the invention has a simplified design, allowing a cost-optimized manufacturing process with the simultaneous improvement in optical display quality.
The invention relates to an operating unit 100 for a household appliance having a touch-sensitive unit 106 and an LED unit 136 positioned on the rear thereof. According to the invention, the touch-sensitive unit 106 is formed with a diffuser foil 116, the top side 118 of which, facing an operator, is provided with a printed character layer 120 and the underside 122 of which, directed away therefrom, is provided with a printed functional layer 124. This leads to a simpler structure of the operating unit 100 with a smaller number of components, which permits a cost-optimized manufacturing process, and also a higher display contrast with the simultaneous reduction of undesirable reflection effects.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 207 158.6 | Jun 2020 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/063850 | 5/25/2021 | WO |
