EP3338292B1 - Operating element for a device having one or more electronic components - Google Patents

Description

The invention relates to an operating element for an electronic and / or an electrical device, in particular for a domestic appliance.

On control elements of an electrical and / or electronic device, highly conductive (metallic or metallized) primary control elements (e.g. a rotary knob) often become non-conductive with other conductive metallic secondary control elements (e.g. with a control panel or with a housing) on the electronics or nearby the electronics of the device. The use of metallic or metallized operating parts is usually desirable for design reasons and / or due to mechanical requirements. However, the electronics of the device can be exposed to an ESD (electrostatic discharge) load when an operator touches a primary control panel. Touching the primary control unit can cause the primary control unit to charge up relatively quickly and then discharge the primary control unit to the secondary control unit (e.g. the housing of the device).

By discharging onto the secondary control panel, i.e. A so-called ESD secondary flashover can lead to high transient electrical and magnetic fields in the area of the electronics of the device. These fields can lead to malfunctions in the electronics or destruction of the electronics.

One way to avoid high transient electrical and magnetic fields is to use highly conductive secondary controls. However, the use of highly conductive secondary controls has several disadvantages. Highly conductive secondary control panels typically make RF (radio frequency) applications (e.g. connecting a device to a WLAN access point) more difficult. Furthermore, highly conductive secondary control panels are usually associated with relatively high costs. In addition, the use of highly conductive secondary controls leads to restrictions in terms of design, mechanics, optics, etc.

US2003 / 0111330 A1 discloses an operating element according to the preamble of claim 1.

The present document deals with the technical task of providing a control element for an electronic device, in particular for a domestic appliance, by means of which secondary flashovers are avoided or at least substantially damped, and yet which RF applications and expanded flexibility with regard to design requirements and / or mechanical Requirements for the electronic device allowed.

The task is solved by the independent claims. Advantageous embodiments include described in the dependent claims.

According to one aspect, a control element for an electronic device or for a device that comprises one or more electronic components is described. The device can comprise a domestic appliance, in particular a domestic appliance.

The control element (which can also be referred to as a design element) comprises an electrically conductive primary part, which is configured to be actuated by a user of the device in order to make an input to the device or to control the device. The primary part can be such that it can be moved by a user for input. In particular, the primary part can comprise a rotary knob or a slider. The primary part can e.g. include a stainless steel.

The control element further comprises an electrically conductive secondary part which is arranged between (and / or in close proximity to) one or more electronic components (e.g. control electronics) of the device and the primary part. The secondary part can have a fixed position relative to the one or more electronic components of the device. For example, the secondary part can comprise an operating panel or a housing of the device. The primary part can have a higher electrical conductivity than the secondary part. Furthermore, the secondary part can be coupled to GND or ground in order to discharge electrical charge.

When the primary part is actuated, a distance (for example a minimal distance) between the primary part and the secondary part can remain unchanged. For example, when using a rotary knob as the primary part, the rotary knob is typically rotated about an axis of rotation, so that even when the The distance (e.g. the minimum distance) between the rotary button and the secondary part (e.g. the control panel or the housing) remains unchanged. Even with a slider, operating the slider typically does not change the distance between the slider and the secondary part (e.g. the control panel or the housing).

In addition, the control element comprises an intermediate layer (which can also be referred to as a connection layer), which is arranged such that the primary part is located on a first side and the secondary part is located on a second side opposite the first side. Furthermore, the intermediate layer can touch the primary part on the first side and / or the secondary part on the second side. The intermediate layer can thus be arranged between the primary part and the secondary part. In particular, the intermediate layer can face the primary part on a first side and face the secondary part on a second side opposite the first side (and possibly touch the primary part and / or the secondary part), so that a secondary flashover of electrostatic charge is damped or avoided from the primary part to the secondary part due to a user touching the primary part by dissipating electrostatic charge from the primary part via the intermediate layer to the secondary part.

Typically there is no direct contact between the primary part and the secondary part. This is particularly advantageous in the case of a movable primary part, in order to be able to move the primary part relative to the secondary part in a comfortable manner. However, the primary part and the secondary part can also be so close to one another in a non-actuated state of the primary part that a secondary rollover from the primary part to the secondary part could occur if a user touches the primary part (also without pressing the primary part to make an entry).

The contact between the primary part and the secondary part can take place indirectly via the intermediate layer when an intermediate layer is provided. The intermediate layer comprises a conductive plastic.

Due to the intermediate layer with conductive plastic, secondary flashovers from the primary part to the secondary part can be avoided or at least substantially dampened. In particular, the electrostatic charge that forms on the primary part when a user touches the primary part can be dissipated from the primary part to the secondary part via the intermediate layer. The derivation can already take place when the primary part is touched by a user, even without actuating the primary part (e.g. without turning a rotary knob or without moving a slider). In particular, the discharge of electrostatic charge due to an existing (indirect) contact between the primary part and the secondary part via the intermediate layer can take place substantially simultaneously with a user touching the primary part. In other words, the primary part, the secondary part and the intermediate layer can be arranged such that when the primary part is touched by a user without actuation of the primary part, the intermediate layer on the first side and the primary part on the second side secondary part touches. This ensures reliable protection of one or more electronic components. Furthermore, the intermediate layer with conductive plastic typically does not provide substantial shielding from electromagnetic radiation in the RF range, so that RF applications are made possible.

The intermediate layer can comprise a plastic with at least one conductive additive. The additive can preferably comprise carbon fibers, conductive carbon black and / or nanotubes. Furthermore, in a cross section of the intermediate layer, which runs from the primary part to the secondary part, the additive preferably has a distribution which deviates by 20%, 10% or less from a uniform distribution. In other words, the distribution of an additive within the intermediate layer is preferably uniform. Reliable discharge of electrostatic charge from the primary part to the secondary part can thus be ensured.

The conductive plastic can be designed in such a way that a transverse resistance of the intermediate layer decreases with increasing voltage between the primary part and the secondary part. For example, the intermediate layer can have a resistance of approximately 16kOhm at a voltage of 10V and one at a voltage of 100V Have a resistance of approx. 10kOhm. Such a voltage-dependent resistor can have the effect that the intermediate layer both enables reliable discharge of electrostatic charge and has the least possible shielding for RF rays.

The intermediate layer can be arranged between the primary part and the secondary part in such a way that, due to a relatively increased permittivity or dielectric conductivity εr of the intermediate layer (compared to the ambient air), field lines of an electric field between the primary part and the secondary part (at least partially) run through the intermediate layer. In particular, the intermediate layer can be arranged between the primary part and the secondary part such that 80%, 90% or more of the field lines of the electric field run through the intermediate layer. Alternatively or additionally, the intermediate layer can be arranged between the primary part and the secondary part in such a way that a relatively strong field increase (relative to the field strength at an outer edge of the intermediate layer) occurs at the intermediate layer. In particular, the field strength in the intermediate layer can be a factor 5, 10 or more higher than the field strength at the outer edge of the intermediate layer. The outer edge of the intermediate layer connects the first side of the intermediate layer with the second side of the intermediate layer. Alternatively or additionally, the intermediate layer can be arranged between the primary part and the secondary part such that the density of field lines of the electric field in the intermediate layer is higher than the density of field lines of the electric field at the outer edge of the intermediate layer. The density of the field lines in the intermediate layer can be a factor of 5, 10 or more higher than at the outer edge of the intermediate layer. In this way, reliable discharge of electrostatic charge (ESD current) from the primary part to the secondary part via the intermediate layer can be ensured. Furthermore, electrical energy of the electrostatic charge can be converted into heat by the electrical resistance of the intermediate layer.

In one example, the primary part comprises a knob with a cavity. The rotary knob can be turned around an axis of rotation. In such a case, the intermediate layer can form a flat ring which is arranged in the cavity of the rotary knob and around the axis of rotation of the rotary knob.

The intermediate layer can have a surface on the second side with an average roughness relative to an average profile of the surface of the second side. The average roughness can have a value of 5%, 10% or more relative to the average profile of the surface of the second side. Roughness on the second side can cause excessive stresses between the intermediate layer and the secondary part. An outflow of electrostatic charge from the primary part to the secondary part can thus be further improved.

In other words, the average course of the surface can e.g. form a flat surface or plane. The actual course of the surface can differ at different points from the flat surface or plane in the positive direction (e.g. towards the secondary part) and / or in the negative direction (e.g. away from the secondary part). For example, a cross section through the second side of the surface of the intermediate layer may have a medium, linear, course, the actual course of the cross section fluctuating around the central, linear, course. The extent of the fluctuations around the mean (linear or flat) course can be indicated by the mean roughness. The mean roughness typically corresponds to the mean amount of deviation of the actual shape of the surface of the second side of the intermediate layer from the mean (linear or flat) shape of the surface of the second side of the intermediate layer. As an alternative to the average roughness, the square roughness can be defined as the mean square deviation of the actual course of the surface of the second side of the intermediate layer from the mean (linear or planar) course of the surface of the second side of the intermediate layer.

As already explained above, a distance (for example a minimum distance) between the primary part and the secondary part can remain unchanged when the primary part is actuated (ie when an entry is made on the device). Furthermore, a distance (for example a minimum distance) between the intermediate layer and the primary part and / or a distance (for example a minimum distance) between the intermediate layer and the secondary part can remain unchanged when the primary part is actuated (in particular with respect to a distance, which is present when the primary part is not operated). In other words, the primary part, the secondary part and the intermediate layer can be arranged such that when the primary is actuated In part (especially during the entire actuation process), a (possibly minimal) distance between the primary part and the intermediate layer remains unchanged (in particular, there may be contact between the primary part and the intermediate layer before and during the actuation of the primary part); and / or a (possibly minimal) distance between the secondary part and the intermediate layer remains unchanged (in particular, there may be contact between the secondary part and the intermediate layer before and during the actuation of the secondary part); and / or a (possibly minimal) distance between the primary part and the secondary part remains unchanged. This is advantageous since mechanical stress on the primary part, the secondary part and / or the intermediate layer can be reduced.

According to a further aspect, an (electronic) device, in particular a domestic appliance, is described, which comprises one or more electronic components and the operating element described in this document.

It should be noted that the devices and systems described in this document can be used both alone and in combination with other devices and systems described in this document. Furthermore, any aspect of the device and systems described in this document can be combined with one another in a variety of ways. In particular, the features of the claims can be combined with one another in a variety of ways.

Figur 1

ein Blockdiagramm eines beispielhaften Hausgeräts (in Frontansicht)

Figur 2

eine Seitenansicht eines beispielhaften Bedienelements; und

Figur 3

beispielhafte Verläufe des Stroms bei einem Sekundärüberschlag.

The invention is described in more detail below on the basis of exemplary embodiments. Show

Figure 1

a block diagram of an exemplary household appliance (in front view)

Figure 2

a side view of an exemplary control element; and

Figure 3

exemplary courses of the current in the case of a secondary flashover.

As stated at the beginning, the present document deals with the provision of a control element for an electrical and / or electronic device, by means of which secondary flashovers can be reduced and the electronics of the device can be protected. Furthermore, the control element should have the least possible shielding for Have electromagnetic radiation in the RF range to enable RF applications of the device.

Fig. 1 shows a block diagram of an exemplary device 100, in particular a household appliance, such as a washing machine, a dishwasher, an oven, etc. The device 100 comprises an operating panel 102 and a rotary knob 101 arranged on the operating panel 102, which enables a user of the device 100 To make entries (e.g. select a program for a household appliance). The control panel 102 can be part of the housing of the electronic device 100. The rotary knob 101 and the control panel 102 can be viewed together as an operating element of the electronic device 100.

The rotary knob 101 can generally be referred to as a primary part or as a primary control part 101 of the control element which is touched by a user of the device 100 in order to make an input to the device 100 or to control the device 100. The primary part 101 is often made of a highly conductive material. When touched, electrical charge can pass from the user to the primary part 101 of the control element. The control panel 102 can be regarded as a secondary part or as a secondary control part of the device 100. This can lead to a secondary rollover in which electrical charge is transferred from the primary part 101 to the secondary part 102.

To avoid an ESD secondary flashover, the control panel 102 or the entire housing of the device 100 can be made of a highly conductive material (for example metal). However, this would lead to shielding of electromagnetic radiation by the control panel 102 or by the housing, which is disadvantageous for RF applications. Alternatively, the control panel 102 or the housing can be constructed from a highly insulating material (eg plastic) without the use of metal parts in the vicinity of the electronics. However, this is typically out of the question for reasons of design and / or stability of device 100. Therefore, moderately conductive materials are typically used to meet design and RF requirements. However, these materials can lead to substantial secondary rollovers.

Fig. 2 shows a control element 200 of a device 100 in a side view. The control element 200 comprises a primary part 101 (for example a rotary knob that can be rotated about an axis of rotation 201) and a secondary part 102 (for example a control panel). Electronics 203 are located behind the secondary part 102 (for example, one or more electronic components for evaluating an input made on the primary part 101). Electronics 203 could be damaged due to a secondary rollover onto secondary part 102.

The control element 200 further comprises an intermediate layer 202, which is arranged between the primary part 101 and the secondary part 102 of the control element 200. The intermediate layer 202 may be in contact with the primary part 101 on a first side and may be in contact with the secondary part 102 on a second side (opposite the first side). Furthermore, the intermediate layer 202 can be arranged between the primary part 101 and the secondary part 102 in such a way that the field lines of an electric field 210 between the primary part 101 and the secondary part 102 (in particular an electric field 210 which results from electrostatic charging of the primary Part 101 originates) through the intermediate layer 202. This condition can be at least partially fulfilled, e.g. 80%, 90% or more of the field lines of the electric field 210 can pass through the intermediate layer 202.

Intermediate layer 202 may include a plastic that includes conductive additives. In other words, the intermediate layer 202 may comprise a conductive plastic. Exemplary conductive additives are materials such as e.g. Carbon fibers (e.g. with a concentration of 8%), conductive carbon black and / or nanotubes e.g. ULTRAFORM® N2320 C BLACK 110 POLYACETAL.

The conductive additives can change the properties of plastics in such a way that the charge of an ESD flashover does not flow over an air gap between the primary part 101 and the secondary part 102 or along the surface of the intermediate layer 202, but rather is conducted in the intermediate layer 202. The conductive additives can be set in such a way that the intermediate layer 202 is relatively low-ohmic for relatively high voltages and relatively high-resistance for relatively low voltages. As a result, the intermediate layer 202 does not substantially attenuate electromagnetic radiation in the RF range. On the other hand, charge can be conducted from the primary part 101 without generating a substantial electric shock through the intermediate layer 202 to the secondary part 102 and possibly from there to ground (GND). The maximum current from the primary part 101 to the secondary part 102 is limited by the resistance of the intermediate layer 202.

Fig. 3 shows exemplary courses 311, 312 of the current 302 over time 301 when the primary part 101 is discharged onto the secondary part 102. In the course 311, a secondary rollover takes place via an air layer between the primary part 101 and the secondary part 102. This secondary rollover points significant current peaks that can affect electronics 203. The course 312 shows the discharge via an intermediate layer 202 with conductive plastic. It can be seen that significant current peaks and the associated risk to the electronics 203 can be avoided.

The structure of an operating element 200 for an electronic device 100 described in this document thus makes it possible to avoid endangering the electronics 203 of the electronic device 100 from secondary flashovers. RF applications are not affected by the control element 200.

The present invention is not restricted to the exemplary embodiments shown. In particular, it should be noted that the description and the figures are only intended to illustrate the principle of the proposed methods, devices and systems.

Claims (10)

1. Operating element (200) for a device (100) which comprises one or more electronic components (203), wherein the operating element (200) comprises

   - an electrically conductive primary part (101) which is designed to be actuated by a user of the device (100), in order to make an input into the device (100);

   - an electrically conductive secondary part (102) which is arranged between the one or more electronic components (203) of the device (100) and the primary part (101); wherein the secondary part (102) is a control panel or a housing of the device (100); and

   - an intermediate layer (202) which comprises a conductive plastic and which faces the primary part (101) on a first side and the secondary part (102) on a second side opposite the first side, such that a secondary flashover of electrostatic charge from the primary part (101) to the secondary part (102) due to a user touching the primary part (101) by dissipation of electrostatic charge from the primary part (101) via the intermediate layer (202) to the secondary part (102) is attenuated or avoided, characterised in that the primary part (101) is a rotary knob or a slider.
2. Operating element (200) according to claim 1, wherein

   - the intermediate layer (202) comprises a plastic with at least one conductive additive; and

   - the additive comprises in particular carbon fibres, conductive carbon black and/or nanotubes.
3. Operating element (200) according to one of the preceding claims, wherein

   - the primary part (101) is such that it can be moved, in particular rotated, by a user for an input; and/or

   - the secondary part (102) has a fixed position relative to the one or more electronic components (203) of the device (100).
4. Operating element (200) according to one of the preceding claims, wherein

   - the primary part (101) is a rotary knob with a cavity;

   - the rotary knob can be rotated about an axis of rotation (201); and

   - the intermediate layer (202) forms a flat ring which is arranged in the cavity of the rotary knob and around the axis of rotation (201) of the rotary knob.
5. Operating element (200) according to one of the preceding claims, wherein

   - the primary part (101) has a higher electrical conductivity than the secondary part (102); and/or

   - the primary part (101) is made from stainless steel.
6. Operating element (200) according to one of the preceding claims, wherein the secondary part (102) is coupled to ground in order to dissipate electrical charge.
7. Operating element (200) according to one of the preceding claims, wherein the device (100) comprises a household appliance, in particular a home appliance.
8. Operating element (200) according to one of the preceding claims, wherein the primary part (101), the secondary part (102) and the intermediate layer (202) are arranged such that when the primary part (101) is actuated

   - a distance between the primary part (101) and the intermediate layer (202) remains unchanged;

   - a distance between the secondary part (102) and the intermediate layer (202) remains unchanged; and/or

   - a distance between the primary part (101) and the secondary part (102) remains unchanged.
9. Operating element (200) according to one of the preceding claims, wherein the primary part (101), the secondary part (102) and the intermediate layer (202) are arranged such that when the primary part (101) is touched by a user without actuation of the primary part (101) the intermediate layer (202) touches the primary part (101) on the first side and the secondary part (102) on the second side.
10. Device (100) which comprises

    - one or more electronic components (203); and

    - an operating element (200) according to one of the preceding claims.

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