Input and output device for a household appliance

Abstract

Input and output device (100, 300) for a household appliance (500, 600), comprising: - a transparent cavity (105) which is filled with a first (110) and a second liquid (115), between which a boundary (117) is formed in the cavity (105); - wherein the liquids (110, 115) have different optical properties; - a pump (120) for pumping the first liquid (110); - a drive unit (125) for the pump (120); and - an electrical control device (150) with an interface (155) for receiving a signal; - wherein the control device (150) is configured to control the drive device (125) in such a way that the boundary (117) between the liquids (110, 115) is moved to a location in the cavity (105) that depends on the received signal, characterized in that - an electrically sensitive layer (160) is attached to the cavity (105) and the control device (150) is configured to determine the position of a human finger (165) on the layer (160) and to provide a position-dependent signal.

Description

[0001] The invention relates to the control of a household appliance. In particular, the invention relates to the input or output of parameters on the household appliance. State of the art

[0002] A household appliance, such as a refrigerator or freezer, a dishwasher, or a washing machine, includes input and output devices through which control or process parameters can be exchanged with a user. Input is often a mechanical control element that can be scanned electrically or electronically. Output is typically achieved using self-illuminating elements. To make it easier for a user to associate an input or output parameter with a specific situation, it is common practice to design the respective input or output element in such a way that it provides at least an implicit indication of the situation.

[0003] One option is to use combined input / output elements similar to a touchscreen. However, a touchscreen of satisfactory quality can be expensive. Furthermore, it can consume a relatively large amount of energy to operate. Controlling the touchscreen may require a processing unit with increased processing capacity. Another alternative involves arrangements with multiple light sources, such as LEDs, which are discretely switched on or off like a bar graph display. This can result in a relatively large current flowing through the arrangement or a control unit, and electrical losses can lead to efficiency or thermal issues. Additionally, the display may use visible light points, which a user could mistakenly interpret as indicating a digital value.

[0004] Input and / or output devices or devices for operating such devices are disclosed in WO 99 / 04532, DE 20 2006 019 447 U1, DE 10 2005 020 433 A1, US 3 973 340 A or DE 199 19 638 A1.

[0005] One objective of the present invention is to provide an improved technique for inputting and outputting a parameter on a household appliance. The invention achieves this objective by means of the subject matter of the independent claim. Dependent claims describe preferred embodiments. Disclosure of the invention

[0006] According to the invention, it has been discovered that the representation or output of a parameter can be improved by means of a transparent cavity filled with a first and a second liquid, between which a boundary is formed. The liquids have different optical properties, in particular different colors, and are moved in or out of the cavity such that the position of the boundary in the cavity represents the parameter. In this way, an immediately perceptible visualization can be created that stands out from known visualizations. The transparent cavity can, in particular, be elongated and comprise, for example, a tube or a hose. Depending on the application, virtually any shape of the cavity is possible, including those whose cross-section varies along their axis of extension.The device can only absorb energy to change the displayed parameter; the actual display can be completely passive.

[0007] An input and output device for a household appliance comprises a transparent cavity filled with a first and a second liquid, between which a boundary is formed in the cavity; wherein the liquids have different optical properties; a pump for conveying the first liquid; a drive device for the pump; and a control device with an interface for receiving a signal; wherein the control device is configured to control the drive device such that the boundary between the liquids is moved to a location in the cavity dependent on the received signal.

[0008] The input and output device can be used to display a parameter, particularly one of electrical or information technology origin, from the control unit of a household appliance. The display can be homogeneous, continuous, and / or easily legible. The output device's installation space can be limited, allowing for easy combination or integration with the household appliance. Readability can be ensured with or without active illumination.

[0009] Representing parameters using liquids can be particularly advantageous when the parameter relates to a liquid or a household appliance that processes liquids. For example, the output device can be used to better visualize water levels, water temperatures, elapsed or remaining processing time in a water bath, or water pressure. The output device can be scaled extensively, allowing for both large-scale visualization using a large-volume transparent cavity and highly miniaturized, compact visualization using small, lightweight, or inexpensive components. A wide variety of pump types and designs can be used to move the liquid.For example, the first fluid can be moved by means of a hydraulic or pneumatic piston, based on a temperature difference, by means of a bi-metal, by means of electromagnetic activation, or in other ways.

[0010] In a further embodiment, the inlet and outlet device comprises a second pump assigned to the second fluid and a second drive unit for the second pump, with the control device configured to control both drive units. By actively controlling both fluids, the prevailing hydraulic pressure in the cavity can be reduced overall, since it is not necessary to maintain the second fluid at a predetermined pressure. This makes it easier to maintain the tightness of the cavity and the hydraulic elements connected to it. The use of two pumps also allows for improved control of the speed at which the boundary within the cavity moves to reflect a change in the parameter.

[0011] According to the invention, an electrically sensitive layer is attached to the cavity, and the control device is configured to determine the position of a human finger on the layer and to provide a position-dependent signal. The cavity can, in particular, carry a highly transparent, resistive, or capacitive layer, similar to a touchscreen, which can be scanned by the control device. When, for example, a human finger is brought into contact with the layer, the finger's position can be determined based on a change in the electrical resistance or capacitance of the layer. The position determines the value of an input parameter. In particular, the determined position can be determined in the direction of the longitudinal extent of the cavity, in which the boundary between the liquids can also be shifted.In this way, both the input and output of parameters can be improved and carried out in an innovative manner.

[0012] The input parameter can, in particular, represent a setpoint and the output parameter an actual value. The relationship between the setpoint and actual value typically concerns the function of a household appliance, which can be controlled by means of a further control unit, preferably connected to the interface of the output unit's control unit. In another embodiment, the output unit is activated to bring the boundary to the position of the touch point, and preferably the input parameter is provided, for example, to a control unit.

[0013] Disclosed is an input device for a household appliance comprising a control element for setting a parameter; a transparent cavity filled with a first and a second liquid, between which a boundary is formed in the cavity; wherein the liquids have different optical properties; and a pump for conveying the first liquid, wherein the pump is coupled to the control element in such a way that the position of the boundary in the cavity depends on a position of the control element.

[0014] Also disclosed is a simple control element whose position is not currently usually visualized separately, which can be provided with a simple and informative visualization by means of the described input device. The input device can be designed in such a way that it does not require an additional power supply. The energy required to move the liquids in the transparent cavity is then preferably supplied by the user operating the control element.

[0015] The input and output device can be used, in particular, to input a parameter that controls a hydraulic or pneumatic process in a household appliance. In one embodiment, the control element is directly integrated or combined with an actuator. For example, a ventilation flap can be adjustable by means of a sliding movement, with the cross-section of the ventilation opening depending on the sliding position. The described input device can be used to display the set parameter, for example, at a remote location or in a special manner adapted to the parameter or its value. Entering a parameter can thus be simplified.

[0016] A scanning device for scanning the parameter is disclosed. The scanning can be performed in a conventional manner at the control element, for example, mechanically, electrically, or optically. In a preferred embodiment, however, a scanning device is provided for determining the position of the boundary in the cavity and for providing a position-dependent signal. The scanning device can, in particular, operate optically, and the signal can be provided, for example, via an interface in an electrical or information technology manner.

[0017] The input and output device comprises the transparent cavity, the liquids that form a boundary within the cavity, and the pump for moving at least one of the liquids. The principle of moving the liquids within the cavity to visualize a parameter can be further refined for both devices.

[0018] For example, the pump can comprise a cylinder with a piston slidably mounted within it. This arrangement can be advantageous for both manual operation, for example in the case of an input device, and for operation by means of a drive unit, for example in the case of an output device. For example, the sealing, manufacturing, or maintenance of such pumps can be simplified based on existing experience with this type of pump.

[0019] It is preferred that neither liquid is soluble in the other. For example, one liquid may be fatty and the other aqueous. In one embodiment, one liquid comprises an oil and the other water or an aqueous solution. The choice of liquids may depend on their optical properties. In particular, a liquid of a specific color may be selected, or the liquid may be selectively colored. One liquid may be transparent and the other wholly or partially opaque. One liquid may also be fluorescent or phosphorescent. In yet another embodiment, one liquid has a daylight fluorescent color, such as yellow or orange.

[0020] In yet another embodiment, the cavity has a sufficiently small cross-section to induce capillarity with at least one of the liquids. This can promote the separation of the two liquids, preventing them from mixing or dissolving into one another and allowing them to form a clearly defined boundary. Capillarity, or the capillary effect, is the behavior of liquids in a narrow tube, gap, or cavity. These effects are caused by the surface tension of the liquid and the interfacial tension between the liquid and the surface of the surrounding cavity. Examples of capillarity include capillary rise and capillary depression.

[0021] In another embodiment, a flow valve is provided to control the flow of one of the liquids. The flow valve can, for example, include a nozzle, i.e., a section with a predetermined flow characteristic. The nozzle typically comprises a cross-sectional constriction in the hydraulic system through which one of the liquids is moved. By appropriately dimensioning the nozzle, it can be ensured that a change in the position of the boundary between the two liquids can occur at a predetermined speed and with a predetermined damping.

[0022] The cavity can be illuminated. In particular, a lighting device can be installed at one end of the cavity. The lighting device can be positioned so that it is not directly visible, yet illuminates one of the two liquids. The illuminated liquid can then glow, especially if it is colored. Light sources can also be installed at opposite ends of the cavity – relative to a possible hydraulic flow direction. Light sources of the same or different colors can be used to influence the color appearance of the two liquids. By directly coupling light into the respective liquid, very little energy can be required for illumination. Thermal problems can be avoided.

[0023] In a particularly preferred embodiment, the lighting device is controllable, specifically with regard to its color or intensity. The control device is preferably configured to control the color or intensity of the lighting as a function of another signal. In particular, the control can be based on the value of the input or output parameter. For example, if the parameter indicates a temperature, a high parameter value can result in warm lighting such as red, while a low parameter value can result in cool lighting such as blue. Absolute values ​​for high or low temperatures can be freely chosen. Other colors or transitions are also possible and can be selected, for example, depending on the nature of the parameter or its range of values. Brief description of the characters

[0024] Embodiments of the invention are now described in more detail with reference to the accompanying figures, in which: Fig. 1 an input and output device for a household appliance; Fig. 2 another embodiment of the input and output device of Fig. 1; Fig. 3 an input and output device for a household appliance; Fig. 4 an embodiment of light coupling to a device according to one of the preceding figures; Fig. 5 an exemplary household appliance with a device according to one of the preceding figures; and Fig. 6 Another exemplary household appliance with several devices is shown according to one of the preceding figures. Detailed description of exemplary implementations

[0025] The accompanying figures show exemplary embodiments of input and output devices for a household appliance, the devices being based on the common concept of the relationship between a parameter and a hydraulic arrangement with two fluids. Features and embodiments of the devices can therefore be combined with one another, as a person skilled in the art will readily recognize.

[0026] Fig. Figure 1 shows a dispensing device 100 for a household appliance. The dispensing device 100 is designed to optically display the value of a parameter relating to the household appliance. For this purpose, the dispensing device 100 includes a transparent cavity 105 filled with a first liquid 110 and a second liquid 115, which form a boundary 117 between them. The liquids 110 and 115 do not mix, so the boundary 117 does not move without movement of the liquids 110 and 115 relative to the cavity 105. To support the permanent separation of the liquids 110, 115, the cross-section of the cavity 105 can be sufficiently small to allow capillarity to occur, or the liquids 110, 115 can be selected accordingly, for example, an aqueous and an oily liquid 110, 115. At the boundary 117, the liquids 110, 115 preferably abut each other directly.In another embodiment, a separating element can also be provided between the liquids 110, 115 in the region of boundary 117, for example a gas bubble, another liquid, or a solid body that is arranged in a cylinder within the cavity in a manner similar to a piston. The separating element is preferably as small as possible to facilitate an unambiguous reading of the position of boundary 117. In one embodiment, for improved reading accuracy, the boundary between one of the liquids 110, 117 and the separating element is considered boundary 117.

[0027] The liquids 110 and 115 preferably differ in their optical properties, for example in their optical densities or colors, so that the boundary 117 can be optically distinguished. In the illustrated embodiment, the first liquid 110 is colored and the second liquid 115 is colorless (transparent). The liquids 110 and 115 can also have different viscosities.

[0028] The cavity 105 is typically formed by a fluid-tight vessel that comprises a transparent material in at least one section, allowing the position of the boundary 117 in this section to be optically detected. The vessel material can be flexible, for example, plastic or silicone, or rigid, for example, glass. The cavity 105 preferably has a longitudinal axis along which it extends. The cross-section of the cavity 105 is preferably constant along this longitudinal axis. Openings for supplying and discharging liquids are preferably provided at opposite ends of the cavity 105. The cavity 105 can also be integrated into an element of the household appliance, for example, by having an appliance wall or shelf support the cavity, or by separating the cavity between elements of the household appliance.The cavity 105 can be of any shape, particularly in the longitudinal direction (along its longitudinal axis), with the illustrated shape of a circular arc or a straight shape being preferred. In one embodiment, the circular arc can also extend around a quarter circle, a semicircle, a three-quarter circle, a full circle, or, in the manner of a helix, around more than one full circle.

[0029] A pump 120 is provided for pumping the first liquid 110, which can be driven by a drive unit 125. The pump 120 and the drive unit 125 can be of any design. In one embodiment, for example, the pump 120 comprises a gear pump or centrifugal pump, while the drive unit 125 comprises an electric motor. In another embodiment, the pump 120 comprises an arrangement of a cylinder with a piston, wherein the drive unit 125 can comprise a linear electromagnetic device. The pumping action of the first liquid 110 into or out of the cavity 105 can also be achieved, for example, by increasing or decreasing the temperature in a closed reservoir. Further embodiments are also conceivable.

[0030] In the illustrated embodiment, a first liquid reservoir 130 is provided to form a supply of first liquid 110 for the pump 120. In one embodiment, the pump 120 is configured to deliver the first liquid 110 in a controllable direction; in another embodiment, delivery in only one direction is possible. Backflow of the first liquid 110 can then be controlled by pressurizing the second liquid 115 accordingly. The first liquid reservoir 130 can be designed to be open or closed, as shown. In one embodiment, a pressure accumulator 135 is provided to absorb hydraulic pressure generated by the pump 120. The position of the boundary 117 can then be adjusted even without direct operation of the pump 120.The direction of the drive unit 125 (at least in one direction) can be altered by controlling a pressure reduction in the region of an opposite end of the cavity 105, which is filled with a second fluid 115. For this purpose, a flow valve 140 can be provided, which in different embodiments can be controlled or uncontrolled. An uncontrolled flow valve 140 can also be called a throttle or nozzle. Second fluid 115 exiting the cavity 105 can be collected in a second fluid reservoir 145 and, if necessary, returned to the cavity 105. In one embodiment, the second fluid reservoir 145 comprises a riser pipe that can be in contact with the environment (atmosphere). In another embodiment, the second fluid reservoir 145 comprises an arrangement of a cylinder and a piston.

[0031] A control device 150 is configured to actuate the drive device 125 in order to change the position of the boundary 117 between the first liquid 110 and the second liquid 115 with respect to the cavity 105 by means of the pump 120. Preferably, the first pump 120 can be actuated depending on a desired flow rate of the first liquid 110. The control device 150 can also influence the controllable flow valve 140 to affect the movement speed of the boundary 117. In one embodiment, a further pump 120 with a further drive device 125 is provided between the cavity 105 and the second liquid container 145, wherein the control device 150 is configured to actuate both drive devices 125.

[0032] The control device 150 comprises an interface 155, in particular for connection with a device for controlling a household appliance, wherein a signal can be received by the control device 150 via the interface 155, indicating the value of a parameter. The control device 150 is preferably configured to influence the liquids 110 and 115 in the cavity 105 such that the position of the boundary 117 in the cavity 105 is changed depending on the signal or the represented value.

[0033] In one embodiment, an electrically sensitive layer 160 is provided on the cavity 105, wherein the control device 150 is connected to the layer 160 in order to scan the position of a human finger 165 on the layer 160 or on the cavity 105. The scanned position or a corresponding value can be provided via the interface 155. In particular, the value can correspond to the same parameter that can be represented by the position of the boundary 117.

[0034] A lighting device 170 can be attached to the cavity 105 such that it illuminates the first liquid 110. For this purpose, the lighting device 170 is preferably arranged in the region of a hydraulic outlet from the cavity 105. The lighting device 170 preferably comprises a light-emitting diode, in particular an integrated multicolor light-emitting diode. The control device 150 can be configured to control the intensity or color of the lighting device 170. Alternatively or additionally, a lighting device 170 can be provided in the region of the other outlet of the cavity 105, which is filled with a second liquid 115. Optionally, one or more cross-sectional changes are provided at predetermined locations on the cavity 105. If one of the liquids 110, 115 flows around a cross-sectional change, this can be perceived by an observer as a point of light or color.This allows the exceeding of a threshold or a specific numerical value to be represented.

[0035] In a further embodiment, the control unit 150 can receive further parameters via the interface 155, which control the display via the output unit 100, such as a flow rate of one of the liquids 110, 115, a color or an intensity of the lighting unit 170.

[0036] Fig. Figure 2 shows another embodiment of the output device 100. Fig. 1. Here, the cavity 105 is shown in an exemplary linear configuration. Two pumps 120 are shown at opposite ends of the cavity 105, again as an example. Both pumps 120 are designed as a combination of a cylinder 205 with a piston 210, which is slidably mounted within the cylinder 205. The linear position of the piston 210 within the cylinder 205 can be controlled by a drive unit 125.

[0037] Fig. Figure 3 shows an input device 300 for a household appliance. The input device 300 is based in essential elements on the output device 100 of the preceding figures, so the reference numerals used therein are retained. The embodiment shown is based in particular on the one in Fig. Figure 2 shows an embodiment of the dispensing device 100 and comprises the transparent cavity 105, which is filled with the first liquid 110 and the second liquid 115, which form a boundary 117 between them. The liquids 110 and 115 have different optical properties. Furthermore, a pump 120 for conveying the first liquid 110 and an operating element 305 are provided, which is coupled to the pump 120 such that a position of the operating element 305 corresponds to a position of the boundary 117 in the cavity 105. In the illustrated embodiment, the pump 120 comprises the arrangement of cylinder 205 and piston 210, which are shown above with reference to Fig. 2 is described in more detail.

[0038] The control element 305 is exemplified as a rotary knob that can be turned to different positions. An eccentric 310 is attached to the control element 305, which influences the position of the piston 210 in the cylinder 205 via a piston rod 315. In another embodiment, the control element 305 can also include, for example, a linearly adjustable slide that acts on the pump 120. The slide can, for example, partially open an opening depending on its position. Such an arrangement can be used, for example, for controlled ventilation or humidity regulation of a vegetable compartment in a refrigerator. In yet another embodiment, the control element 305 can also include a button.

[0039] In the illustrated example, the control element 305 can be rotated such that the eccentric 310 drives the piston 210 further into the cylinder 205, thereby forcing the first liquid 110 out of the cylinder 205 into the cavity 105. As a result, the second liquid 115 is displaced from the cavity 105, for example into a riser pipe or a second liquid reservoir 145. Fig. 1 or the illustrated arrangement consisting of cylinder 205 and piston 210. The piston 210 can be loaded by means of an elastic element 320 to ensure that when the control element 305 is turned back in conjunction with the release of the piston 210 of the pump 120 containing the first liquid 110, the arrangement returns to its original position until the piston rod 315 rests against the eccentric 310 again. Through these processes, the position of the boundary 117 between the liquids 110 and 115 in the cavity 105 can be controlled depending on the position of the control element 305.

[0040] The control element 305 can directly trigger a control operation, for example, by opening or closing a passage or by initiating a similar mechanical action. The control element 305 can also be electrically scanned to provide the value of a parameter, for example, by including a potentiometer. In a further embodiment, a scanning device 325, particularly an optical one, is provided to determine the parameter value and thus the position of the boundary 117 in the cavity 105. Scanning can also be performed at another location within the hydraulic arrangement. For example, the position of one of the pistons 210 or a hydraulic pressure in the hollow body 105 can be scanned in a known manner. Preferably, the control unit 150 is connected to the scanning device 325 and configured to provide the scanned value via the interface 155.

[0041] Fig. Figure 4 shows an embodiment of light coupling into the cavity 105 of one of the devices 100, 300 of the preceding figures. An exemplary linear cavity 105 is shown, at one end of which a first liquid reservoir 130 for receiving a first liquid 110 is attached. The first liquid reservoir 130 is exemplary designed as a bellows, so that it can also function as a pump 120 or pressure accumulator 135 (cf. Figure 4). Fig. 3) In the region of the end of the cavity 105, a bend 405 of the cavity 105 or its hydraulic feed, which receives the first liquid 110, is provided. A transparent extension 410, to which the lighting device 170 is attached, is provided in a straight extension of the direction of extension of the cavity 105 in the end region. For this purpose, the extension 410 can have an end face that extends as perpendicularly as possible to the desired direction of light flux in the direction of extension of the cavity 105. In another embodiment, the lighting device 170 is recessed in a recess in the extension 410. Light from the lighting device 170 is thus preferably coupled into the first liquid 110 in the direction of extension of the cavity 105. The first liquid 110 can scatter the coupled light at least partially in a lateral direction, so that an observer perceives a luminous liquid.The preferred effect is to achieve a homogeneous distribution of the coupled light in the liquid 110, 115.

[0042] In other embodiments, the light can also be coupled from the first liquid 110 into the second liquid 115 across the boundary 117. The illumination device 170 can also be provided at the end of the hollow body where the second liquid 115 is usually located. Other methods of coupling light into the hollow body 105 or into one of the liquids 110, 115 can use a prism or a mirror. The light is coupled into the liquids 110, 115 as uniformly as possible, with as little light as possible falling directly from the illumination device 170 into the eye of an observer.

[0043] The lighting device 170 preferably comprises a light-emitting diode (LED), which can be monochromatic or multichromatic. A multichromatic LED is typically formed by several semiconductors that are configured to emit differently colored light (e.g., red, green, and blue) and are arranged close together. By varying the intensities of the individual semiconductors, light of a predetermined mixed color can be generated. A first liquid 110, illuminated with colored light, can adopt the light color or change it to another color. The intensity of the light can be controlled by rapidly switching the lighting device 170 on and off at a predetermined duty cycle. The intensity can be adapted to the ambient light conditions or the time of day. The lighting device 170 can also be configured to emit white or pseudo-white light.The liquids 110, 115 can also be illuminated in different colors or intensities by means of associated lighting devices 170.

[0044] Fig. Figure 5 shows an exemplary household appliance 500 with a device 100, 300 according to one of the preceding figures. The household appliance 500 shown comprises a washing machine with a round door 505. Along the curvature of the door 505 is a circular arc-shaped cavity 105 according to the illustration of Fig. 1. The cavity 105 can be located on the door 505 itself or radially further outwards, on a body of the household appliance 500. The position of the boundary 117 between the first liquid 110 and the second liquid 115 can be used in the manner described for the input or output of a parameter, which is particularly related to the operation of the household appliance 500.

[0045] Fig. Figure 6 shows another exemplary household appliance 600 with several devices 100, 300 according to one of the Fig. 1 to 4. The household appliance 600 comprises an exemplary stove with four cooking zones 605. Each cooking zone 605 is assigned a device 100, 300. Controlling a cooking zone 605 by means of one of the devices 100, 300 can, in particular, include inputting or outputting a setpoint or actual value of a power level or temperature of the cooking zone 605. In one embodiment, the temperature of the cooking zone can act on a sealed first liquid container 130, so that the necessary pumping action for moving the boundary 117 is already ensured by the temperature-induced expansion of the first liquid. In this sense, the devices 100, 300 can also be used practically as remote thermometers.

[0046] The statements made above and the advantages mentioned can be considered exemplary for the respective intended embodiment. Reference sign 100 output device 105 cavity 110 first liquid 115 second liquid 117 border 120 pump 125 Drive unit 130 first liquid container 135 pressure accumulators 140 Flow valve 145 second liquid container 150 control unit 155 Interface 160 shifts 165 fingers 170 Lighting equipment 205 cylinders 210 pistons 300 Input device 305 Control element 310 eccentric 315 Piston rod 320 elastic element 325 scanning device 405 bend 410 extension 500 Household appliance (washing machine) 505 Door 600 Household appliance (stove) 605 Cooktop

Claims

[1] Input and output device (100, 300) for a household appliance (500, 600), comprising: - a transparent cavity (105) which is filled with a first (110) and a second liquid (115), between which a boundary (117) is formed in the cavity (105); - wherein the liquids (110, 115) have different optical properties; - a pump (120) for pumping the first liquid (110); - a drive unit (125) for the pump (120); and - an electrical control device (150) with an interface (155) for receiving a signal; - wherein the control device (150) is configured to control the drive device (125) in such a way that the boundary (117) between the liquids (110, 115) is moved to a location in the cavity (105) which depends on the received signal, characterized by , that - an electrically sensitive layer (160) is attached to the cavity (105) and the control device (150) is configured to determine the position of a human finger (165) on the layer (160) and to provide a position-dependent signal. [2] Input and output device (100, 300) according to claim 1, further comprising a further pump (120) associated with the second liquid (115) and a further drive device (125) for the further pump (120), wherein the control device (150) is configured to control both drive devices (125). [3] Input and output device (100, 300) according to one of the preceding claims, wherein the pump (120) comprises a cylinder (205) with a piston (210) slidably received therein. [4] Input and output device (100, 300) according to one of the preceding claims, wherein neither of the liquids (110, 115) is soluble in the other liquid (110, 115). [5] Input and output device (100, 300) according to one of the preceding claims, wherein the cavity (105) has a sufficiently small cross-section to effect capillarity with at least one of the liquids (110, 115). [6] Input and output device (100, 300) according to one of the preceding claims, further comprising a flow valve (140) for controlling the flow of one of the liquids (110, 115). [7] Input and output device (100, 300) according to one of the preceding claims, further comprising a lighting device (170) at one end of the cavity (105). [8] Input and output device (100, 300) according to claim 7, wherein the control device (150) is configured to control the color or intensity of the illumination depending on a further signal.

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