WO2020025096A1

WO2020025096A1 - Contact- and/or proximity-sensitive input device and method for producing such an input device

Info

Publication number: WO2020025096A1
Application number: PCT/EP2018/000385
Authority: WO
Inventors: Walter Kulmus; Uwe Heimann
Original assignee: Diehl Ako Stiftung & Co. Kg
Priority date: 2018-08-03
Filing date: 2018-08-03
Publication date: 2020-02-06
Also published as: DE112018007887A5

Abstract

The invention relates to a contact and/or proximity-sensitive input device, having a printed circuit board (12) and a support (14) made of an opaque plastic material. The support (14) has at least one light channel (18), which extends through the support in the thickness direction of the support, and at least one sensor element (28, 36) made of an electrically conductive elastic plastic material, said sensor element being integrated into a recess (24) in the support. The light channel (18) forms a lighting surface (20) on the support (14) face facing a user, and the sensor element (28, 36) forms a sensor surface (26) of a capacitive contact switch on the support (14) face facing the user. The printed circuit board (12) is equipped with at least one light source (22) for coupling light into a light channel (18) of the support (14) and at least one electrically conductive contact surface (30) for contacting a sensor element (28, 36) in the support (14). The printed circuit board (12) is arranged on the support (14) face facing away from the user, and the support (14) is mounted on the printed circuit board (12).

Description

Touch and / or proximity sensitive input device and method for producing such an input device

The present invention relates to a touch and / or proximity sensitive input device, in particular for household appliances, and a method for producing such an input device.

Touch and / or proximity sensitive input devices often use capacitive touch switches, in which a sensor element made of an electrically conductive material together with, for example, a user's finger via a control panel made of an electrically insulating material as a dielectric forms a capacitance therebetween, which capacitance or not depending on the touch Touching or approaching or not approaching a control panel of the control panel assigned to the sensor element is variable. The change in the capacitance value of the sensor element has a corresponding effect on an output signal of the sensor circuit, which can be processed and evaluated by evaluation electronics.

Recently, sensor foils with integrated conductive sensor surfaces are being used more and more frequently for the construction of compact input devices with illuminated displays. Disadvantages are the high costs of such sensor foils, the complex electrical connection of the sensor surfaces to a printed circuit board and also the temperature sensitivity of such sensor foils, which shortens the life of the input device in environments with higher temperatures, such as in hobs.

It is the object of the invention to provide an improved touch-sensitive and / or proximity-sensitive input device with capacitive sensor elements and illuminated displays, which has a simple structure and a longer service life. This problem is solved by the teaching of the independent claims. Particularly advantageous refinements and developments of the invention are the subject of the dependent claims.

The touch and / or proximity sensitive input device of the invention has a carrier made of an opaque plastic material and a printed circuit board. The carrier has at least one light channel, which extends through the carrier in a thickness direction, and at least one sensor element made of an electrically conductive, elastic plastic material, which is integrated in a recess in the carrier, the light channel facing a user On the side of the carrier forms an illuminated surface and the sensor element on the side of the carrier facing a user forms a sensor surface of a capacitive touch switch. At least one light source for coupling light into a light channel of the carrier and at least one electrically conductive contact surface for contacting a sensor element in the carrier are arranged on the circuit board, the circuit board being arranged on the side of the carrier facing away from a user and the carrier on the PCB is mounted.

According to the invention, it is proposed to create a structural unit from a carrier with integrated light channels and integrated sensor elements and at the same time to mount them mechanically and electrically on a printed circuit board, as a result of which structure and assembly effort can be simplified and manufacturing costs can be reduced. By using an electrically conductive, elastic plastic material for the sensor elements, a large-area and thus safe / reliable contact with the contact surfaces of the printed circuit board can be guaranteed. The use of an electrically conductive, elastic plastic material is also more temperature-resistant (e.g. up to 160 ° C and more) and also mechanically more resistant than sensor foils, so that the susceptibility to interference of the input device is reduced and the life of the input device can be extended.

The input device of the invention is particularly suitable for electronic household appliances such as hobs, stoves, dishwashers, laundry treatment devices, refrigerators and / or freezers and the like. The one according to the invention is particularly advantageous Input device for household appliances with higher temperatures such as hobs, stoves and the like.

Conductive silicone or conductive TPE (thermoplastic elastomer) is preferably used as the electrically conductive, elastic plastic material for the sensor elements. The electrical conductivity of the plastic material is achieved, for example, by embedded / vulcanized fillers, wires or the like.

The sensor areas can be individual sensor areas for individual touch keys or several combined sensor areas for, for example, rotary controls or slide controls.

The input device preferably contains a multiplicity of luminous areas and a multiplicity of sensor areas which are provided by a single carrier.

The luminous surfaces formed by the light channels can be illuminated / backlit symbols, simple light point displays, 7-segment light displays and the like. The light sources on the circuit board are preferably light-emitting diodes. One or more light sources can optionally be provided for each light channel.

The light channels can have a substantially constant cross section, an expanding cross section or a tapering cross section along the thickness direction of the carrier. The light channels preferably run essentially perpendicular to the thickness direction through the carrier. In addition, the channel walls of the light channels can optionally be designed to reflect light. Optionally, the light channels can also be at least partially filled with a transparent plastic material (e.g. polycarbonate).

In a preferred embodiment of the invention, at least one electrically conductive contact pin is mounted on the contact surface of the printed circuit board, which protrudes into the sensor element in the recess in the carrier. A contact pin is preferably provided for each sensor element. The contact pins are preferably mounted as SMD components on the circuit board. By protruding the contact pins into the elastic sensor relemente a large and thus safe electrical contact can be guaranteed.

In one embodiment of the invention, the sensor element is an electrically conductive plastic compound that is injected into the recess in the carrier, preferably by means of a 2-component injection molding process.

In another embodiment of the invention, the sensor element is a preformed, electrically conductive plastic molded part which is inserted into the recess in the carrier, preferably pressed in and / or glued / fused.

In one embodiment of the invention, a diffuser film is arranged on the side of the carrier facing a user. The diffuser film is a light-scattering film for equalizing the brightness of the light radiated through the light channels. The diffuser film is preferably glued to the carrier. The diffuser film can be a printed or unprinted diffuser film and a colored, colored or colorless diffuser film.

In a further embodiment of the invention, the input device also has a housing for holding and protecting the printed circuit board. The housing can protect the printed circuit board from mechanical loads, moisture or water, high temperatures and the like in, for example, a household appliance. If required, a further circuit board can also be held in the housing, which is electrically connected to the circuit board and is arranged non-parallel to the circuit board. The further circuit board is used, for example, for a power module.

The method according to the invention for producing a touch-sensitive and / or proximity-sensitive input device includes the steps of forming a carrier from an opaque plastic material with at least one light channel, which extends through the carrier in a direction of thickness, and at least one recess for receiving a sensor element; integrating at least one sensor element made of an electrically conductive, elastic plastic material into the at least one recess in the carrier; the provision of a printed circuit board on which at least one light source for coupling light into a light channel of the Carrier and at least one electrically conductive contact surface for contacting a sensor element are arranged in the carrier; and mounting the carrier with the at least one integrated sensor element on the printed circuit board, the contact surface of the printed circuit board coming into contact with the sensor element of the carrier when the carrier is mounted.

With this manufacturing method, the same advantages as with the input device of the invention described above can be achieved. With regard to definitions of terms and preferred configurations, reference is also made to the above explanations in connection with the input device.

In a preferred embodiment of the invention, an electrically conductive contact pin is mounted on the contact surface of the circuit board, so that when the carrier is mounted on the circuit board it penetrates into the sensor element in the recess in the carrier.

In one embodiment of the invention, the sensor element is formed from an electrically conductive plastic compound (e.g. conductive silicone or conductive TPE), which is injected into the recess in the carrier. Depending on the design of the recess (s) in the carrier, the areas of the injected plastic compound form individual sensor elements or at least one insulation gap is generated in the plastic compound injected into the recess in the carrier in order to form at least two sensor elements that are electrically separated from one another.

In another embodiment of the invention, the sensor element is preformed as an electrically conductive molded plastic part, which is then inserted into the recess in the carrier.

In a further embodiment of the invention, the light channel in the carrier can be at least partially filled with a transparent plastic material.

In yet another embodiment of the invention, a diffuser film is applied to the side of the carrier facing a user. The above and other features and advantages of the invention can be better understood from the following description of preferred, non-limiting exemplary embodiments with reference to the accompanying drawing. It shows, mostly schematically:

1 is a partial sectional view of an input device according to an embodiment of the present invention;

FIG. 2 shows a partial perspective view of a carrier for the input device from FIG. 1 according to an exemplary embodiment of the present invention; FIG.

3 shows a top view of a carrier for the input device of FIG. 1 according to an exemplary embodiment of the present invention; Fig. 4 is an exploded view of an input device according to another

Embodiment of the present invention; and

5 shows a perspective view of an input device according to a further exemplary embodiment of the present invention.

1 to 3, a first exemplary embodiment of an input device according to the invention is explained in more detail.

The input device has an operating panel 10, which can be formed, for example, by a glass ceramic plate of a hob. On the side of the control panel 10 facing away from the user (bottom in FIG. 1), a printed circuit board 12 is arranged at a distance and essentially parallel to the control panel 10. A carrier 14 is mounted on the printed circuit board 12 on the side of the printed circuit board 12 facing the control panel 10. On the side of the carrier 14 facing the control panel 10, a diffuser film 16 is applied, preferably glued, to the carrier 14.

The carrier 14 is formed from an opaque plastic material (preferably hard plastic), preferably by means of injection molding, and has an essentially cuboid basic shape. As shown in Fig. 1, the carrier 14 is for example by means of locking lugs 42, which are guided through openings 40 in the printed circuit board 12, are fastened to the printed circuit board 12.

A plurality of light channels 18 are provided in the carrier 14 and extend through the carrier 14 in the thickness direction thereof. Optionally, these light channels can be filled with a translucent plastic material (e.g. polycarbonate) and / or can be designed with light-reflecting channel walls. A plurality of light-emitting diodes are mounted on the printed circuit board 14 as light sources 22 corresponding to the light channels 18, so that the light channels 18 each form a light-emitting surface 20 on their side facing the control panel 10.

A plurality of cutouts 24 are also provided in the carrier 14. The recesses 24 are each filled with an electrically conductive, elastic plastic compound (e.g. conductive silicone or conductive TPE), preferably by means of two-component injection molding, in order to form sensor elements 28. Corresponding to the cutouts 24, a plurality of contact surfaces 30 are provided on the printed circuit board 12, which are equipped with contact pins 32 using SMD technology. The contact pins 32 protrude into the elastic sensor elements 28, so that the sensor elements 28 are in electrically conductive contact with the contact surfaces 30 of the printed circuit board 12. As a result, the sensor elements 28 each form a sensor surface 26 of a capacitive touch switch on their side facing the control panel 10.

As can be seen from FIGS. 1 to 3, the cutouts 24 and the sensor elements 28 extend on the one hand to the side of the carrier 14 facing the printed circuit board 12. On the other hand, the cutouts 24 and the sensor elements 28 extend to the side of the control panel 10 facing the Carrier 14, the design being adapted to the shape of the desired sensor surfaces 26.

If the recess 24 extends over a plurality of sensor surfaces 26, the injected plastic compound must be provided with insulation gaps 34 in order to electrically isolate the individual sensor elements 28 from one another. The insulation gaps 34 can be formed, for example, by cutting or punching out. Alternatively, the carrier 14 is designed in such a way that the cutouts 24 are each only over one Extend sensor surface 26 so that no insulation gaps 34 have to be created.

As illustrated in FIG. 3, for example, a row of sensor areas 26 forms a touch-sensitive slider (lower area of FIG. 3) and a row of luminous areas 20 is provided below and above the row of sensor areas in order to provide the user with the activated level of, for example Slider and the level values of the slider. In another area of the carrier 14, a plurality of groups of luminous areas 20 are provided, each of which forms a 7-segment luminous display. In addition to these 7-segment light indicators, sensor areas are provided for forming touch-sensitive buttons.

The diffuser film (or scatter film) 16 can be printed or unprinted, depending on the application. In addition, the diffuser film 16 can be colored, colored or colorless.

In the manufacture of this input device, a printed circuit board 12 with contact surfaces 30 is initially provided, which is equipped with light sources 22 and contact pins 32, preferably using SMD technology. In addition, a carrier 14 is formed with light channels 18 and recesses 24, the recesses 24 of which are then filled with the electrically conductive plastic compound, preferably by means of two-component injection molding, and if necessary subsequently provided with insulation gaps 34. The structural unit of the carrier 14 with the integrated sensor elements 28 is then mounted on the printed circuit board 12, the electrical contact between the contact surfaces 30 and the sensor elements 28 taking place simultaneously with the mechanical fastening. The diffuser film 16 can optionally be applied before or after the mounting of the carrier 14 on the printed circuit board 12.

4 illustrates a second embodiment of an input device of the invention. Corresponding components are identified by the same reference numerals as in the first exemplary embodiment.

In this exemplary embodiment, the sensor elements 36 are formed by preformed components made of an electrically conductive, elastic plastic material (for example conductive silicon cone or conductive TPE). The plastic components are inserted into the corresponding recesses 24 in the carrier 14, preferably pressed in and optionally additionally glued or fused. The contact pins 32 on the printed circuit board 12 then also penetrate into these plastic molded parts.

Otherwise, the input device of FIG. 4 and its manufacture correspond to the first exemplary embodiment of FIGS. 1 to 3.

5 illustrates a third embodiment of an input device of the invention.

The third exemplary embodiment represents an extension of the first or second exemplary embodiment. The printed circuit board 12 with the carrier 14 mounted thereon is held in / on a housing 44. The housing 44 protects the printed circuit board 12, for example, from mechanical loads, moisture, water, high temperatures, etc. In addition, the housing 44 can optionally also hold another printed circuit board 44, for example for a power module. In the embodiment of FIG. 5, the further printed circuit board 44 is oriented at a right angle to the printed circuit board 12 (generally not parallel to the printed circuit board 12).

REFERENCE NUMBER LIST

10 control panel

12 printed circuit board

14 carriers

16 diffuser film

18 light channel

20 illuminated area

22 light source, in particular light-emitting diode

24 recess

26 sensor surface

28 sensor element as conductive mass 30 contact surface

32 contact pin

34 insulation gap

36 sensor element as conductive molded part

40 breakthrough

42 latch

44 housing

46 more circuit boards

Claims

Touch and / or proximity-sensitive input device, in particular for a household appliance, comprising:

a carrier (14) made of an opaque plastic material, the at least one light channel (18) which extends through the carrier in a thickness direction thereof, and at least one sensor element (28, 36) made of an electrically conductive, elastic plastic material which is in a Recess (24) is integrated in the carrier, the light channel (18) on the side of the carrier (14) facing a user forming a luminous surface (20) and the sensor element (28, 36) on the side of the carrier facing a user (14) forms a sensor surface (26) of a capacitive touch switch; and

a printed circuit board (12) on which at least one light source (22) for coupling light into a light channel (18) of the carrier (14) and at least one electrically conductive contact surface (30) for contacting a sensor element (28, 36) in the carrier ( 14) are arranged, the circuit board (12) being arranged on the side of the carrier (14) facing away from a user and the carrier (14) being mounted on the circuit board (12).

The input device of claim 1, wherein

an electrically conductive contact pin (32) is mounted on the contact surface (30) of the printed circuit board (12) and protrudes into the sensor element (28, 36) in the recess (24) of the carrier (14).

An input device according to claim 1 or 2, wherein

the sensor element (28) is an electrically conductive plastic compound which is injected into the recess (24) in the carrier (14).

An input device according to claim 1 or 2, wherein

the sensor element (36) is a preformed, electrically conductive plastic molded part which is inserted into the cutout (24) in the carrier (14).

5. Input device according to one of the preceding claims, wherein the light channel (18) is at least partially filled with a transparent plastic material.

6. Input device according to one of the preceding claims, in which

A diffuser film (16) is arranged on the side of the carrier (14) facing a user.

7. Input device according to one of the preceding claims, which

further comprises a housing (44) for holding and protecting the printed circuit board (12).

8. The input device of claim 7, wherein

A further circuit board (46) is held in the housing (44), which is electrically connected to the circuit board (12) and is arranged non-parallel to the circuit board (12).

9. A method for producing a touch- and / or proximity-sensitive input device, in particular for a household appliance, with the steps:

Forming a carrier (14) from an opaque plastic material with at least one light channel (18) extending through the carrier in a thickness direction and at least one recess (24) for receiving a sensor element (28, 36),

Integrating at least one sensor element (28, 36) made of an electrically conductive, elastic plastic material into the at least one recess (24) in the

Straps (14),

Providing a printed circuit board (12) on which at least one light source (22) for coupling light into a light channel (18) of the carrier (14) and at least one electrically conductive contact surface (30) for contacting a sensor element (28, 36) in the carrier (14) are arranged, and

Mounting the carrier (14) with the at least one integrated sensor element (28, 36) on the printed circuit board (12), the contact surface (30) of the printed circuit board (12) when mounting the carrier (14) with the sensor element (28, 36) of the carrier (14) comes into contact.

10. The method of claim 9, wherein

an electrically conductive contact pin (32) is mounted on the contact surface (30) of the printed circuit board (12) so that when the carrier (14) is mounted on the printed circuit board (12) in the sensor element (28, 36) in the recess (24) of the carrier (14) penetrates.

1 1. The method of claim 9 or 10, in which

the sensor element (28) is formed from an electrically conductive plastic compound which is injected into the recess (24) in the carrier (14).

12. The method of claim 1 1, in which

at least one insulation gap (34) is generated in the plastic compound injected into the recess (14) in the carrier (14) in order to form at least two electrically separated sensor elements (28).

13. The method of claim 9 or 10, wherein

the sensor element (36) is preformed as an electrically conductive molded plastic part, which is then inserted into the recess (24) in the carrier (14).

14. The method according to any one of claims 9 to 13, in which

the light channel (18) in the carrier (14) is at least partially filled with a transparent plastic material.

15. The method according to any one of claims 9 to 14, in which

a diffuser film (16) is applied to the side of the carrier (14) facing a user.