DE102021125965A1 - Touch-sensitive input device - Google Patents

Abstract

An input device has a contact surface, a sensor frame (14) and a rear base part. The sensor frame (14) has two long sides (44) and two short sides (46) connecting the long sides (44). There are exactly two force sensor units (53) on each long side (44) and exactly one force sensor unit (53) on each short side (46). The arrangement of the force sensor units (53) is selected such that each force sensor unit (53) on the long sides (44) is a distance S2,i in a direction parallel to the long sides and a distance S1,i in a direction parallel to the short side, to the respective force sensor unit on the near short side (46). Furthermore, the considered i-th force sensor unit (53) of the longitudinal sides (44) has a distance S3,i to the other force sensor unit (53) of the same longitudinal side (44) and the ratio Ri=(S1,i+S2,i)/S3,i for each of the four longitudinal side force sensor units (53) in the range of 0.7 to 1.2.

Description

The invention relates to a touch-sensitive input device.

With such input devices, touching of the input device by a user is detected and a corresponding electrical signal is output, for example to a central electronic control system.

Illustrative examples of such input devices are touch screens (also known as touch screens), which use a resistive, a capacitive or an inductive contact surface to detect a user touch and emit a corresponding electrical (touch) signal that contains additional information about the position of the touch the contact surface includes.

For example, in the case of input devices in motor vehicles, it is advantageous for the force of the touch to be determined in addition to touching the input device. In this way, for example, intentional touching can be distinguished from unintentional touching of the input device.

For this purpose, input devices are known from the prior art that have a plurality of force sensors that detect the force exerted on the input device.

It is a particular challenge to provide a uniform scanning sensitivity over the entire contact area of the input device.

In this context, a uniform scanning sensitivity means that the pressure values measured by the force sensors result in the same value in total or on average, regardless of the area of the contact surface in which the force acts on the contact surface.

It is therefore the object of the invention to improve the scanning sensitivity of an input device.

The object is achieved by a touch-sensitive input device that has a rectangular shape. The input device includes a front contact surface touchable by a user, a front sensor frame, and a rear base. Between the contact surface and the base part, an elastic intermediate layer is provided at least in sections along the edge of the sensor frame, which allows displacement of the contact surface in the direction of the base part when force is applied. The sensor frame has two long sides and two short sides connecting the long sides. The length of the long sides is greater than the length of the short sides and there are exactly two force sensor units each with at least one force sensor on each long side and exactly one force sensor unit each with at least one force sensor on each short side. The arrangement of the force sensor units is selected in such a way that the force sensor units on the long sides, in a direction parallel to the long sides, each have a distance S _2,i to the respective force sensor unit on the near short side, where i = 1, 2, 3, 4 and indicates the force sensor unit under consideration on one of the two long sides. Furthermore, the considered i-th force sensor unit of the long sides has a distance S _3,i to the other force sensor unit of the same long side, and the force sensor units arranged on the short sides are measured in a direction parallel to the short sides, each at a distance S _1,i positioned to the considered i-th force sensor unit of the long side.

It is now crucial that the ratios R _i = (S _1,i + S _2,i ) / S _3,i for each of the four force sensor units on the longitudinal sides are in the range from 0.7 to 1.2, with i = 1 , 2, 3, 4 indicates the considered force sensor unit of the longitudinal sides.

In particular, the input device can have a length-to-width ratio between 10:1 and 1:1 or between 4:1 and 5:4.

The positions and distances of the force sensor units are each determined using a reference point of the respective force sensor unit, with the reference points lying in a plane parallel to the plane of the sensor frame and, in a projection perpendicular to this plane, indicating the geometric center of that area of the force sensor unit in which they are located supported either on the base part or on the front contact surface.

The arrangement of the force sensor units is selected in particular such that the force sensor units on the short sides are positioned in a range of ±10% of the length of the short side around the middle of the respective short sides.

The invention is based on the finding that irregularities in the scanning sensitivity of input devices arise in particular when an elastic intermediate layer is attached in the power flow path between the contact surface and the base part. Due to the elastic intermediate layer, the mechanical are advantageous physical stresses on the contact surface are reduced, but the sensing sensitivity of the input device is also degraded. The invention starts from this finding and improves the scanning sensitivity in that the force sensors are positioned at very specific positions along the sensor frame.

The elastic intermediate layer is, for example, a damping tape (also known as damping tape). Such an intermediate layer is also used for optical shielding and/or dust sealing.

The user can make an entry on the input device via the contact surface.

It is conceivable that the contact surface is designed to be touch-sensitive.

The contact surface can therefore be formed with a known resistive, optical, capacitive or inductive measuring layer, which detects a touch on the contact surface by the user and provides an electrical signal dependent on the touch position.

Alternatively or additionally, the position of the touch can also be detected using the force sensors.

The force sensor units are usually embedded in the sensor frame. The embedding of the force sensor units enables a compact configuration of the input device.

In some advantageous configurations of the invention, provision is made for the force sensor units with the force sensors to be arranged centrally on the short sides. In this way, the arrangement of the force sensor units is symmetrical on the sensor frame. The symmetrical arrangement has a positive effect on the scanning sensitivity.

In one embodiment of the invention, the ratio R for each of the force sensor units is in the range of 0.85 to 0.95. In practice, this ratio has proven to be advantageous for input devices with a length/width ratio of between 10:1 and 2.3:1, in particular between 5:1 and 5:4.

The force sensor units on the short sides are preferably positioned in a range of ±10% of the length b of the short side around the center of the short side.

Preferably, all force sensor units of the long sides are arranged such that they each have an equal distance to their respective near short sides (46), so that S _2.1 = S _2.2 = S _2.3 = S _2.4 applies.

The force sensor units on the short sides can in particular be arranged in the middle, in each case at 50% of the length b of the respective short sides.

Furthermore, it can be provided that the force sensor units on the short sides, relative to the center of the short sides, are offset in the same direction in the transverse direction of the input device.

In some configurations, the force sensor units on the short sides are offset in opposite directions relative to the center of the short sides, viewed in the transverse direction of the input device. This can be necessary, for example, because of external specifications, for example specifications for the arrangement of a cable connection.

In some developments, it is provided that the two force sensor units on the same long side have different distances S _2,i to their respectively close short side. In this case, that force sensor unit has a smaller distance S _2,i whose distance S _1,i is greater.

To put it simply, those force sensor units in the direction in which a force sensor unit close to the short sides is offset are arranged further away from this short side.

In one embodiment of the invention, a panel coupled to the sensor frame is provided, which has the contact surface. In this way, some area for user input is made available to the user. The user is thus provided with an interface via which the user can interact with the input device.

For example, the user can draw lines on the panel with a pen, the course of which is recorded and transmitted via an interface to a terminal such as a computer or laptop. The force measured by the force sensors can be used, for example, to adjust a line width or a line thickness.

Icons or buttons can also be displayed on the panel. By touching a corresponding symbol or a corresponding button, the user can make an entry on the input device.

In one embodiment of the invention, the panel is an LCD panel optically bonded to a protective glass on which information is displayed to the user. By touching displayed control elements or displayed information, the user can make an input on the input device.

The base part can be a backlight unit for the LCD panel. In this way, the input device is very compact. In this case, the backlighting unit serves to illuminate the corresponding representations on the LCD unit of the display unit with light. For this purpose, the liquid crystals in a liquid crystal display are controlled in such a way that they influence the direction of polarization of the light of the backlighting unit.

A further aspect of the invention provides that the panel is attached to the sensor frame or is surrounded at the front edge by the sensor frame. Thus, a force on the contact surface of the input device, i. H. on the panel, transferred directly to the sensor frame, so that the sensing sensitivity is further improved.

The sensor frame can also form part of the contact surface. In this way, the force acting on the sensor frame can be recorded directly. This can be advantageous in particular in the case of an input device without a display.

In one embodiment of the invention, the elastic intermediate layer is positioned between the panel and the sensor frame. In this way, the panel is protected from excessive deformation.

In order to provide the largest possible contact surface, the elastic intermediate layer can have a width which corresponds to the width of the sensor frame in the region of the sensor frame adjoining the intermediate layer. This can be advantageous in particular for achieving the greatest possible holding force. In many configurations, however, a small width of the elastic intermediate layer can also be advantageous, so that the force exerted can be measured as precisely as possible. For example, the width of the elastic intermediate layer is smaller than the width of the sensor frame and is approximately in the range between 5% and 80%, in particular in the range from 20% to 70% of the width of the sensor frame. In this way, force leakage paths can be minimized and the measurement accuracy increased in this way. At the same time, a seal can be achieved, in particular to prevent scattered light from escaping and/or to prevent moisture, dust and other particles from penetrating.

The elastic intermediate layer can have a width greater than 500 μm, which means, for example, that it is easy to handle during production.

In one embodiment of the invention, each force sensor is accommodated in a measuring section in the sensor frame. In this case, an elastic element is arranged or formed in the measuring section, which has a reduced thickness compared to the adjacent section or sections of the sensor frame. A special measuring range is thus provided on the sensor frame.

In this case, the elastic element has the reduced thickness, in particular in a direction which is perpendicular to the contact surface. In this way, the action of a force leads to a comparatively strong deformation of the elastic element, which is detected by the force sensors.

Outside the areas containing the elastic elements, the sensor frame can be of uniform thickness.

For example, the sensor frame has a number of measuring sections corresponding to the number of force sensors, in which the elastic elements force sensors are embedded.

In the measuring sections, the elastic elements can be designed as measuring beams. The measuring bars can be firmly connected to the sensor frame on one side, in particular formed integrally on the sensor frame, and supported on the other side on the contact surface or the base part. In this way, the force exerted by the user on the contact surface is recorded via an intermediate element (measuring bar), thus further improving the scanning sensitivity of the input device.

Alternatively, instead of the measuring beams, elastic elements (measuring bridges) connected to the sensor frame at both ends can also be arranged in the measuring sections on both sides. The measuring beams or measuring bridges can each have a fastening section which is arranged, or formed, in particular perpendicularly to the longitudinal direction of the measuring beam or the measuring bridge. The fastening section can be designed, for example, in the form of a projection or a fastening projection. For transferring the force exerted on the contact surface by the user to the elastic element, in particular the measuring beam or the measuring bridge, the fastening section is supported and/or fastened, for example, on the contact surface or the base part.

For example, the attachment protrusion is a tab.

For example, each force sensor is a strain gauge that registers an elongation, i.e. a stretching or compression of the elastic element. Strain gauges make it possible to measure even small forces.

Of course, each force sensor can also have more than one strain gauge.

For example, the at least one strain gauge is embodied in a Wheatstone measuring bridge. In this way, the sensitivity of the force sensor is further improved, in particular since interference such as temperature fluctuations and the influence of changes in humidity can be reduced.

It is conceivable that the measuring bridge is designed as a half bridge (with two strain gauges and two resistors) or as a full bridge (with a total of four strain gauges).

The force sensors can be fixed to the respective elastic element by means of a non-positive connection. The attachment of the force sensor to the surface takes place in particular adhesively, e.g. by means of a gluing process or by an injection process, in particular a plastic injection process, in which the force sensor was previously inserted into the cavity of the tool.

• - 1 eine perspektivische Seitenansicht einer erfindungsgemäßen Eingabevorrichtung gemäß einer ersten Ausführungsform,
• - 2 eine Seitenansicht der Eingabevorrichtung der 1 ohne einen Abdeckrahmen,
• - 3 die Eingabevorrichtung der 1 bei weggelassener Kontaktfläche in einer perspektivischen Ansicht,
• - 4 eine Seitenansicht und eine Draufsicht eines der Messabschnitte der Eingabevorrichtung aus 3
• - 5 eine perspektivische Detailansicht eines Messabschnitts der Eingabevorrichtung der 3,
• - 6 eine Draufsicht auf einen Sensorrahmen der Eingabevorrichtung der 1 bis 4,
• - 7 eine weitere beispielhafte Ausgestaltung des Sensorrahmens der Eingabevorrichtung bei weggelassener Kontaktfläche in einer Draufsicht,
• - 8 eine weitere beispielhafte Ausgestaltung des Sensorrahmens der Eingabevorrichtung bei weggelassener Kontaktfläche in einer Draufsicht,
• - 9 eine weitere beispielhafte Ausgestaltung des Sensorrahmens der Eingabevorrichtung bei weggelassener Kontaktfläche in einer Draufsicht,
• - 10 eine weitere beispielhafte Ausgestaltung des Sensorrahmens der Eingabevorrichtung bei weggelassener Kontaktfläche in einer Draufsicht,
• - 11 eine weitere beispielhafte Ausgestaltung des Sensorrahmens der Eingabevorrichtung bei weggelassener Kontaktfläche in einer Draufsicht,
• - 12 eine weitere Ausgestaltung eines Messabschnitts einer erfindungsgemäßen Eingabevorrichtung,
• - 13 ein Messabschnitt einer erfindungsgemäßen Eingabevorrichtung in einer weiteren Ausgestaltung, und
• - 14 eine Seitenansicht einer erfindungsgemäßen Eingabevorrichtung gemäß einer zweiten Ausführungsform.

Further advantages and features of the invention result from the following description and from the accompanying drawings, to which reference is made below. In the drawings show:

• - 1 a perspective side view of an input device according to the invention according to a first embodiment,
• - 2 a side view of the input device of FIG 1 without a cover frame,
• - 3 the input device 1 with omitted contact surface in a perspective view,
• - 4 Fig. 12 shows a side view and a top view of one of the measuring sections of the input device 3
• - 5 a perspective detailed view of a measuring section of the input device of FIG 3 ,
• - 6 a plan view of a sensor frame of the input device of FIG 1 until 4 ,
• - 7 a further exemplary configuration of the sensor frame of the input device with the contact surface omitted in a plan view,
• - 8th a further exemplary configuration of the sensor frame of the input device with the contact surface omitted in a plan view,
• - 9 a further exemplary configuration of the sensor frame of the input device with the contact surface omitted in a plan view,
• - 10 a further exemplary configuration of the sensor frame of the input device with the contact surface omitted in a plan view,
• - 11 a further exemplary configuration of the sensor frame of the input device with the contact surface omitted in a plan view,
• - 12 a further embodiment of a measuring section of an input device according to the invention,
• - 13 a measuring section of an input device according to the invention in a further embodiment, and
• - 14 a side view of an input device according to the invention according to a second embodiment.

1 FIG. 1 shows a touch-sensitive input device 10 having a front-side contact surface 12, a sensor frame 14 and a rear-side base part 16. FIG. The front contact surface 12 means that side which usually faces a user.

The input device 10 has a rectangular shape, and the contact surface 12, the sensor frame 14 and the base part 16 are also designed to be rectangular.

Thus, the input device 10 has a length l and a width b. In the 1 the ratio of length to width is 2.4:1. Due to the perspective distortion, the ratio of the lengths of the drawn arrows results in a different value. The width b thus corresponds to the length of a short side and the length I corresponds to the length of a long side.

In general, the input device 10 has an aspect ratio of 4:1 to 2:1.

In the first embodiment, the contact surface 12 is formed by a panel 18 and a cover frame 20, more precisely by a front-side section 22 of the cover frame 20, which extends parallel to the panel 18. Thus, a section 24 of cover frame 20, which extends laterally along sensor frame 14, does not form part of contact surface 12.

Panel 18 in the is an example 1 formed as an LCD panel 26 (also known as a liquid crystal screen, LCD unit) and the base part 16 as a backlight unit 28 . The Indian 1 The cover frame 20 shown may vary in shape or may be absent in some configurations of the input device. For example, in automotive applications, it is also common for the LCD unit to be directly integrated into an environment, such as embedded in an instrument panel.

In a manner known per se, the backlight unit 28 and the LCD panel 26 information 30 on a in the 1 visible area 32 of the LDC panel 26 is displayed. The area 32 corresponds to the contact surface 12 without the section 22 of the cover frame 20.

For example, the information 30 is a button or an icon.

In general it is also conceivable that the information 30 is permanently printed on the panel 18 . In this case, the panel 18 is not in the form of an LCD panel 26 .

By touching the information 30, ie by touching the contact surface 12, a user can make an entry on the input device 10. The position of the input is recorded and a predetermined function is carried out based on the recorded position.

For example, the LCD panel 26 is a capacitive LCD panel 26 for this purpose and accordingly has a thin layer of conductive material.

To put it more precisely, the input device 10 is connected to control electronics 34 , for example via an interface formed on the input device 10 . The electronic control unit 34 receives an electrical signal which is dependent on the position of the touch and on the basis of which the electronic control unit 34 determines which information 30 has been touched.

A function corresponding to the touched information 30 is stored in the control electronics 34, for example in a memory 36 of the control electronics 34. As soon as the control electronics 34 detects that the information 30 has been touched, the corresponding function is started.

For example, the control electronics could switch to a new display by touching the information 30 or perform an action, for example start route navigation for a motor vehicle or play a specific song via an audio system of a motor vehicle.

As schematically in the 2 shown, the sensor frame 14 is arranged spatially between the contact surface 12 and the base part 16 and is materially connected to the contact surface 12 and the base part 16 via an elastic intermediate layer 38a, 38b, for example glued.

A total of six measuring sections 42 are formed on sensor frame 14, with exactly two measuring sections 42 being formed on each of the longitudinal sides 44 of sensor frame 14 extending in the longitudinal direction and exactly one measuring section 42 being formed on each of the short sides 46 of sensor frame 14 extending in the transverse direction.

As in particular from the 3 until 5 shows, each measuring section 42 is a recess 48 of the sensor frame 14, within which a force sensor unit 53 is arranged. In the embodiment shown, each force sensor unit 53 comprises a force sensor 54 and a measuring beam 50 .

Each measuring beam 50 has a deformation section 52 to which the force sensor 54 is attached, and a fastening section 56 which is molded onto the deformation section 52 and extends perpendicularly away from the deformation section 52 .

The force sensor 54 can be attached to a surface of the measuring beam 50, in particular in the area of the deformation section 52, for example by means of a non-positive connection. In particular, the force sensor 54 can be attached to the measuring beam 50 adhesively, by gluing or by an injection molding process. In some configurations it can be advantageous if the force sensor is arranged on a printed circuit board, in particular on a flexible printed circuit board, and the printed circuit board is glued onto the deformation section 52 .

In principle, the force sensor 54 can be arranged both on an underside pointing in the direction of the base part 16 and on an upper side of the measuring beam 50 pointing in the direction of the contact surface 12 . In some configurations, the force sensor 54 can be at least partially in be embedded in the deformation section 52 . For this purpose, the force sensor 54 can be inserted into a cavity of an injection molding tool before a plastic injection molding process. An embedding of the force sensor 54 so that it does not protrude or does not protrude completely over a surface of the deformation section 52 can be carried out by means of a film back-injection process.

In the example of 4 one of the elastic intermediate layers 38a, 38b, for example the elastic intermediate layer 38a, is designed in such a way that it absorbs as little force as possible. In this variant, the force F exerted on the contact surface 12 is thus transmitted completely and directly to the sensor frame 14 . The fastening sections 56 of the measuring bars 50 are then supported against the base part 16, so that the movement of the sensor frame 14 relative to the base part 16 caused by the force F is decisive for the force measurement. The elastic intermediate layer 38a is therefore provided here in particular as a seal against escaping light and against penetrating moisture and penetrating particles, for example dust, and can be made comparatively hard.

In the embodiment shown, the orientation of the attachment section 56 is selected in the direction of the base part 16 . In other configurations, an alignment in the direction of the contact surface 12 can also be provided. The alignment, i.e. in the direction of the base part 16 or in the direction of the contact surface 12, determines a preferred characteristic (hard or soft) of the intermediate layers 38a and 38b. Here, the base part can always be considered as a "mass", i.e. as approximately "stationary",

If the fastening sections 56 are aligned in the direction of the base part 16, the sensor frame 14 and the contact surface 12 preferably move as a unit when force is applied to the contact surface 12. This unit is displaced in the direction of the base part 16. In this case, the force F, or the flow of force, must be transmitted to the base part 16 via the fastening sections 56 . In order to ensure this, the elastic intermediate layer 38b between the sensor frame 14 and the base part 16 is preferably designed to be as soft as possible. Thus, power flow leakage through the intermediate elastic layer 38b can be minimized. It can be advantageous here if the elastic intermediate layer 38b between the contact surface 12 and the sensor frame 14 ensures the strongest possible connection to the sensor frame 14 . This can be desirable, for example, in an automobile display, since in the event of an accident this is the only way to hold the display and a cover glass attached to it.

In the other case, when the fastening sections 56 are aligned in the direction of the contact surface 12, the sensor frame 14 and the base part 16 form a “unit”. These can therefore be firmly connected to one another. In this embodiment, the contact surface 12 must be displaceable in the direction of the sensor frame 14 . On the one hand, the intermediate layer 38a arranged between the contact surface 12 and the sensor frame 14 should not be too hard in order not to cause leakage of the flow of force, but on the other hand it must meet specifications for a minimum carrying load. Thus, in applications in the automotive sector, it can again be ensured that the display and the associated cover glass are held reliably even in the event of an accident. In order to prevent splinters from forming in the event of an accident, a circumferential bond can be formed between the display and the cover glass.

In other words, depending on the selected preferred direction, the elasticity of the intermediate layers 38a and 38 is selected such that when a force F acts on the contact surface 12, either the contact surface 12 moves in the direction of a unit comprising the sensor frame 14 and the base part 16, or where the contact surface 12 and the sensor frame 14 move towards the base part 16 as a unit.

In the example, the elastic intermediate layers 38a and 38b are completely along the front and back edges 40 ( 5 ) of the sensor frame 14 is arranged.

In the example, the elastic intermediate layers 38a and 38b thus have a width b _Z which corresponds to the width b _R of the edge 40 of the sensor frame 14 in the respective area of the sensor frame 14 .

In other words, the widths b _R and b _Z can be both in the area of a measuring section 42 and in an area between two measuring sections 42 (cf. 3 ) adapted to each other, in particular be the same. Such a configuration can be advantageous when the fastening sections 56 are aligned in the direction of the contact surface 12 . Thus, a display unit such as a display can be fixed well.

In configurations with an opposite orientation of the fastening sections 56 (in the direction of the base part 16), it can be advantageous if the intermediate layer 38b arranged between the sensor frame 14 and the base part 16 has a smaller width than the sensor frame 14 in this area. As a result, the power flow leakage can be further minimized, while still being able to achieve a good seal.

In some configurations only one elastic intermediate layer 38a, 38b can be provided. An elastic intermediate layer (38a) is arranged between the sensor frame 14 and the contact surface 12 or the base part on that side of the sensor frame 14 on which the fastening sections of the elastic elements are arranged. The second elastic intermediate layer (38b) can be missing on the opposite side. A seal can then be arranged, for example, on the outer circumference in order to prevent the escape of scattered light or the penetration of moisture and particles.

The force sensors 54 are strain gauges, for example, which are arranged in a Wheatstone measuring bridge.

For example, each force sensor 54 is designed as a full bridge and accordingly has a total of four strain gauges that are interconnected in a ring or a square.

Alternatively, each or only individual force sensors 54 can be designed as a half-bridge. The force sensor 54 can be arranged, for example, on a flexible printed circuit board, which is attached to the elastic element (here the measuring beam 50). Appropriate wires or flexible printed circuit boards can be used to contact the force sensors 54, which are routed along, for example, in or on the sensor frame 14 for connection to a control circuit.

The measuring bar 50 is firmly connected to the sensor frame 14 at a first end 58 . More specifically, each scale bar 50 is integrally formed with the sensor frame 14 at the first end 58 .

For example, the sensor frame 14 is made of plastic and the recesses 48 and the measuring bar 50 are formed on the sensor frame 14 by means of an injection mold.

In this case, the force sensors 54 are molded onto the corresponding deformation sections 52 of the measuring beams 50 . The force sensors 54 were thus already inserted into the measuring sections 42 during the injection molding of the sensor frame 14 .

At a second end 60, which is formed by the attachment section 56, the measuring bar 50 is connected to the base part 16; Alternatively or additionally, the connection can also be made in a different way, for example by means of a positive connection or by gluing. The measuring bar 50 is therefore only attached to the sensor frame 14 at one end and not at the other end.

In the 4 is a section X of a measurement section 42 of FIG 3 shown in a side view and a top view. A force sensor unit 53 is arranged in the measuring section 42 . The force sensor unit 53 includes an elastic element that is designed as a measuring bar 50 . A force sensor 54 is arranged on the measuring beam 50 . To transmit the force, the measuring beam has a fastening section 56 which is fastened to the base part 16 here.

To determine the distance and position of the force sensor unit 53, a reference point R is shown, which is given by the intersection of a plane parallel to the input surface and a line running perpendicular to this plane through the geometric center of the fastening section 56.

Another detail of the input device, with a perspective view of a measuring section 42 is in FIG 5 shown. From the 5 shows, among other things, that the measuring bar 50 in the area of the measuring section 42 has a smaller extension d ₂ perpendicular to a plane of the contact surface 12 than a thickness d ₁ of the sensor frame 14 in an area outside of the measuring section 42. The extension d ₂ in the measuring section 42 the maximum extent of the measuring section perpendicular to the contact surface 12 is understood.

However, the extension d ₂ is advantageously selected to be large enough that the movement of the measuring section 42 in the direction perpendicular to the contact surface is limited. The maximum force acting on the force sensor 54 can thus be limited. On the one hand, this can protect against damage to the force sensor 54 or the elastic element. On the other hand, the range of possible measured values can thereby be reduced or limited, as a result of which a higher resolution of the measured values can be possible in some configurations of the force sensor 54 .

When a user acts on the force F on the contact surface 12, first the elastic intermediate layer 38 between the contact surface 12 and the sensor frame 14, then the sensor frame 14 and finally the elastic intermediate layer between the sensor frame 14 and the base part 16 are deformed.

After the measuring beams 50 are attached to the base part 16 via the corresponding attachment sections 56, the deformations are deformed Measurement sections 52 of the measuring beam 50 as a function of the position of the force F and the amount of the force F, ie the force exerted.

A plurality of measuring beams 50 are usually measurably deformed by the force F applied. This deformation is detected by the corresponding strain gauges and thus by the corresponding force sensors 54 . Each force sensor 54 provides a corresponding electrical signal and transmits this to the control electronics 34.

The electrical signals include information about both the magnitude of the force and the point of contact of the user's input so that the control electronics 34 can determine the position of the applied force F and the magnitude of the applied force F from the electrical signals from the force sensors 54 .

The contact surface 12 therefore does not have to be designed to be touch-sensitive.

For example, the electronic control unit 34 only performs a function if the user acts on the contact surface 12 with a certain amount of force F.

Alternatively, the function can also be force-dependent, i.e. dependent on the amount of force F. For example, a firm press, i.e. an action with a comparatively large amount of force F, would lead to a different function than a light press.

Corresponding signal lines can be embedded in the sensor frame 14, which are connected to a connection element 62 ( 6 ), for example a ribbon cable, to the force sensors 54 are routed. For reasons of clarity, the signal lines are not shown. The connection element can also be arranged on the inside, i.e. in the area enclosed by the sensor frame, and can be routed to the outside, for example, via a recess on the back of the base part for contact.,

In order to have a high level of sensitivity when measuring the force acting on the contact surface 12, the force sensors 54 are arranged in a very specific relationship to one another.

The force sensor units 53 on the transverse short sides 46 are in the configuration of FIG 6 placed in the middle. This arrangement is in 6 indicated by the center line 64, which also passes through the corresponding reference points R.

The arrangement was therefore chosen such that the reference point R is located at 50% of the length of the short side 46 .

In general, the force sensor units 53 are arranged on the short sides 46 in an area 63 which corresponds to 40% to 50% of the length of the short side 46 .

In other words, as an alternative to the configuration shown, the force sensor units 53 can also have an offset in the transverse direction relative to the center of the corresponding short side 46 .

The force sensor units 53 on the longitudinal sides are at a distance S _1,i from the center line in the transverse direction, measured from the respective reference point R. In the embodiment shown, the force acts on an attachment portion 56 of the measuring beam 50, so that the measuring beam 50 is deflected in proportion to the applied force. As explained above, the reference point R is thus given here as the geometric center of the fastening section 56 in the plan view shown.

On the long side 44, the force sensors 54 are arranged at a distance S _3.1 from one another and each have a distance S _2.1 from the near short side 46 in the longitudinal direction (again measured in relation to the reference points R of the corresponding force sensor units 53).

The resulting ratios R _i , formed from the quotient of the sum of the distances S _1,i and S _2,i to the distance S _3,i , is 0.9 in the embodiment shown.

Preferably, the ratio R ranges from 0.85 to 0.95. This special arrangement of the force sensors ensures a particularly high scanning sensitivity of the input device 10 . In particular, with the arrangement of the force sensors 54 with the ratio R _i , not only the amount of the force F can be measured, but also the position of the force F.

The 7 shows an alternative embodiment of the sensor frame 14, in which case compared to 6 a different orientation of the measuring bar 50 was selected. In the 6 the measuring bars 50 arranged on the long sides 44 of the sensor frame 14 are each fastened to the sensor frame 14 on their side closer to the respective short side 46 . The measuring beams 50 of the force sensors on one longitudinal side 44 are therefore arranged with their fastening sections 56 facing one another. The measuring bars 50 of the short sides 46 are arranged in such a way that their fastening sections 56 are located at opposite ends of the relative to one another Measuring bars 50 are arranged. In the 7 the two measuring bars 50 arranged on the same longitudinal side 44 are now aligned in the same direction, the fastening sections 56 are therefore each arranged on an end of the measuring bar 50 pointing in the same direction. Furthermore, the measuring bars 50 of the longitudinal sides 44 are arranged in the opposite direction to the measuring bars 50 lying on the respectively opposite longitudinal side 44 of the sensor frame 14 .

In the 8th a further configuration of the arrangement of the measuring bars 50 is illustrated. The alignment of the measuring bars 50 corresponds here to that in FIG 6 orientation shown. However, an offset of the measuring bars 50 arranged on the short sides 46 relative to the center line is provided here. The measuring bar 50 arranged on one short side is therefore arranged in the transverse direction at a distance S4 from the reference point R of the relevant force sensor arrangement 53 from the center line. The measuring bar 50 arranged on the other short side 46 is now offset in the opposite transverse direction from the center line by the distance S4.

The one in the 9 shown embodiment shows a development of the embodiment of 8th . In order to at least partially compensate for the asymmetrical (transversely offset from one another) arrangement of the measuring bars arranged on the short sides, an asymmetrical arrangement of the measuring bars 50 on the long sides is also provided here. In each case, that measuring bar on a longitudinal side 44 that is in the 8th is located closer to a measuring bar 50 of the short sides 46 is in the embodiment of 9 arranged offset in the longitudinal direction by an amount S5 in the direction of the other measuring bar of this longitudinal side.

Another alternative embodiment of the sensor frame 14 is in 10 shown. In this example, the measuring bars 52 point in a direction perpendicular to the direction in which the respective side (transverse side 46 or longitudinal side 44) of the sensor frame 14 extends. The measuring bars 50 point in the direction of the respective opposite side of the sensor frame 14.

Furthermore, the measuring bars 50 can be completely surrounded by the sensor frame 14 in a plane of the sensor frame 14, which lies parallel to the input plane, as in FIG 11 shown. The orientation of the measuring bars 50 and their arrangement relative to each other can also be analogous to that in FIGS 6 until 9 embodiments shown vary.

Based on 12 until 13 further configurations of the input device 10 are explained below. The configurations essentially correspond to the first embodiment, so that only the differences are discussed below.

In the design of 12 the second end 60 of the measuring bar 50 is not attached to the base part 16 but to the contact surface 12 .

In other words, the fastening section 56 is fastened to the contact surface 12, ie to the panel 26, for example.

In this embodiment, a force F acting on the contact surface 12 leads directly to an elongation, i.e. a stretching or compression of the deformation section 52 in the area of the force sensor 54 relative to the sensor frame 14.

Another difference is that the force sensor 54 is not embedded in the deformation section 52, but is glued to the deformation section 52, i.e. to the measuring beam 50.

In the design of 13 For example, a force sensor unit with a measuring bridge 66 instead of the measuring beam 50 is formed in the measuring section 42 . The sensor frame 14 thus has a recess 68 on the upper side, into which the force sensor 54 is glued.

A fastening projection 70 is formed on the measuring bridge 66 , via which the measuring bridge 66 is supported on the base part 16 or is fastened to the base part 16 .

In general, the fastening projection 70 can also be arranged on the side of the measuring bridge 66 which faces the contact surface 12 .

The fastening projection 70 is preferably formed in one piece with the measuring bridge 66 and is arranged centrally on the measuring bridge.

Furthermore, the associated force sensor 54 is arranged on the side of the measuring bridge 66 which is opposite the fastening projection 70 . In this case, the force sensor 54 can be arranged both centrally and to the left and/or to the right of the fastening projection.

The 14 shows a second embodiment of the input device 10, which is essentially the embodiment of FIG 1 until 7 corresponds, so that only the differences will be discussed in the following.

In contrast to the first embodiment, the input device 10 has only one intermediate layer 38 via which the base part 16 and the sensor frame 14 are connected to one another. The panel 18 rests directly on the sensor frame 14 and the sensor frame 14 encloses the panel 18 by means of hook-shaped extensions 72.

The sensor frame 14 thus surrounds the panel 26.

The sides 74 of the extensions 72 that face away from the sensor frame 14 form part of the contact surface 12.

In other words, the sensor frame 14 is part of the contact surface 12.

In general, it is also conceivable for a groove to be formed laterally on the sensor frame 14, into which the panel 18 is inserted.

In this case, the sensor frame 14 completely surrounds the panel 18 in the edge area of the panel 18 .

Reference List

10

input device

12

contact surface

14

sensor frame

16

base part

18

panel

20

cover frame

22, 24

Sections of the cover frame

26

LCD panel

28

backlight unit

30

information

32

Area

34

control electronics

36

Storage

38a, 38b

intermediate layers

40

edge

42

measurement section

44

long side

46

shortside

48

Recess of the sensor frame

50

measuring bar

52

deformation section

53

force sensor unit

54

force sensor

56

attachment section

58

first end

60

second end

62

connection element

63

Area

64

centerline

66

measuring bridge

68

recess

70

mounting boss

72

extension

74

pages

R

Reference points of the force sensor units for determining the distance

S1,i S2,i S3,i

Distances with respect to the i-th force sensor units

S4

Distance of the short side force sensor unit to the center line

S5

Offset of the force sensor unit of the long side in the longitudinal direction

Claims (23)

Touch-sensitive input device having a rectangular shape with a front contact surface (12) touchable by a user, a front sensor frame (14) and a rear base part (16), wherein between the contact surface (12) and the base part (16 ) an elastic intermediate layer (38a, 38b) is provided at least in sections along the edge (40) of the sensor frame (14), which allows the contact surface (12) to be displaced in the direction of the base part (16) when force (F) is applied, wherein the sensor frame (14) has two long sides (44) and two short sides (46) connecting the long sides (44) and on each long side (44) exactly two force sensor units (53) each with at least one force sensor (54) and on each short side ( 46) there is in each case exactly one force sensor unit (53) each with at least one force sensor (54); wherein the arrangement of the force sensor units (53) is selected such that the force sensor units (53) of the longitudinal sides (44), in a direction parallel to the longitudinal sides, each have a distance S _2,i to have the respective force sensor unit on the near short side (46), where i=1, 2, 3, 4 and indicates the force sensor unit (44) of the two long sides (44) under consideration; wherein the considered i-th force sensor unit (53) of the longitudinal sides (44) has a distance S _3,i to the respective other force sensor unit (53) of the same longitudinal side (44); wherein the force sensor units (53) arranged on the short sides (46) are each positioned in a direction parallel to the short sides (46) at a distance S _1,i from the i-th force sensor unit under consideration on the long side (44), and wherein the Ratio R _i = (S _1,i + S _2,i ) / S _3,i for each of the four force sensor units (53) of the longitudinal sides is in the range of 0.7 to 1.2. input device claim 1 , characterized in that the ratios R _i are respectively in the range 0.85 to 0.95, with i = 1, 2, 3, 4. input device claim 1 or 2 , characterized in that the force sensor units (53) on the short sides (46) are positioned in a range (63) of ±10% of the length (b) of the short side (46) around the center of the short side (46). Input device according to one of Claims 1 until 3 characterized in that the force sensor units (53) are arranged centrally on the short sides (46), in each case at 50% of the length (b) of the respective short sides (46). Input device according to one of Claims 1 until 3 , characterized in that the force sensor units (53) on the short sides (46) are arranged offset in the same direction in the transverse direction of the input device relative to the center of the short sides (46). Input device according to one of Claims 1 until 3 , characterized in that the force sensor units (53) on the short sides (46) are offset in opposite directions relative to the center of the short sides (46) in the transverse direction of the input device (10). input device claim 6 , characterized in that the two force sensor units (53) of the same long side (44) are at different distances S _2,i from their respectively close short side (46), with that force sensor unit (53) having a smaller distance S _2,i whose distance S _1,i is greater. Input device according to one of Claims 1 until 6 , characterized in that all force sensor units (53) of the long sides (44) have the same distance to their respective near short sides (46), so that S _2.1 = S _2.2 = S _2.3 = S _2.4 applies . Input device according to one of the preceding claims, characterized in that the sensor frame (14) forms part of the contact surface (12). Input device according to one of the preceding claims, characterized in that a panel (18) which is coupled to the sensor frame (14) and has the contact surface (12) is provided. input device claim 10 , characterized in that the panel (18) is an LCD panel (26). input device claim 11 , characterized in that the base part (16) is a backlight unit (28) for the LCD panel (26). Input device according to one of Claims 10 until 12 , characterized in that the panel (18) is mounted on the sensor frame (14) or is surrounded at the front edge by the sensor frame (14). Input device according to one of Claims 10 until 13 , characterized in that the elastic intermediate layer (38a) is positioned between the panel (18) and the sensor frame (14). Input device according to one of Claims 1 until 13 , characterized in that the elastic intermediate layer (38b) is arranged between the sensor frame (14) and the base part (16). input device Claim 14 or 15 , characterized in that a second elastic intermediate layer (38a, 38b) is present, the second elastic intermediate layer (38b) in the case of Claim 14 is arranged between the sensor frame (14) and the base part (16) and wherein the second elastic intermediate layer (38a) in the case of Claim 15 is arranged between panel (18) and sensor frame (14). input device Claim 16 , characterized in that the second elastic intermediate layer (38a, 38b) has a smaller elasticity than the elastic intermediate layer (38a, 38b). Input device according to one of the preceding claims, characterized in that the elastic intermediate layer (38a, 38b) has a width (bz) which corresponds to the width (b _R ) of the edge of the sensor frame (14) in the intermediate layer (38) adjacent area of the sensor frame (14). Input device according to one of Claims 1 until 17 , characterized in that the elastic intermediate layer (38a, 38b) has a width (bz) in the range of 20% to 70% of the width (b _R ) of the edge of the sensor frame (14) in the area of the sensor frame adjoining the intermediate layer (38). (14) owns. Input device according to one of the preceding claims, characterized in that each force sensor (54) is accommodated in a resilient measuring section (42) in the sensor frame (14), the measuring section (42) having a reduced thickness (d ₂ ) compared to the one or the adjacent ones Has sections of the sensor frame (14). Input device according to one of the preceding claims, characterized in that the force sensors (54) are each designed as strain gauges. Input device according to one of the preceding claims, characterized in that the force sensors (54) are each arranged on a deformation section (52) of a measuring bar (50), the measuring bar (50) being attached to the sensor frame (14) at a first end (58) is attached and is supported or attached at an opposite second end (60) to the contact surface (12) or the base part (16) for transmitting the force (F) to the force sensor (54). Input device according to one of Claims 1 until 22 , characterized in that the force sensors (54) are each arranged on a deformation section (52) of a measuring bridge (66), the measuring bridge (66) being fastened to the sensor frame (14) at both ends and the measuring bridge having a fastening projection (70 ) which is supported or fastened on the contact surface (12) or on the base part (18) in order to transmit the force (F) to the force sensor (54).

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