Method for manufacturing a strain meter device, strain meter device and use of said device

Abstract

The invention relates to a method for producing a strain gauge device, to a strain gauge device (20) and to the use of the device. The method comprises: obtaining (110) a first substrate (21A), preferably a first moldable substrate film (21A), for housing electronic components; printing (120) the strain metering device (22) on the first substrate (21A) by a method of printing electronic devices, such as by screen printing or inkjet printing; and molding (140), preferably by means of injection molding, a layer (23) of a molding material that encases the strain gauge device (22). The strain dose apparatus (20) may comprise two preferably formable substrate films, between which the strain metering device (22) and the molding material layer (23) may be arranged.

Description

[0001] This application is a divisional application of an invention patent application with an application date of December 21, 2018, application number "201811573027.4", and invention name "Method of manufacturing strain measuring equipment, strain measuring equipment and use of the equipment".

[0002] The project leading to this application has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 725076. Technical Field

[0003] The present invention relates generally to the technical field of electronic devices, associated apparatus, structures, uses thereof and methods of manufacture. However, in particular but not exclusively, the present invention relates to the manufacture of strain gauge devices using moulding such as injection moulding and such devices and uses thereof. Background Art

[0004] Typically, there are a variety of different multilayer assemblies and structures in the context of electronics and electronic products. The motivations behind the integration of electronics and related products may be as diverse as the associated use environments. When the resulting solution ultimately exhibits multilayer properties, it is relatively often sought to save size, save weight, save materials, save costs, performance gains, or simply effectively fill the components. In turn, the associated use scenarios may involve product packaging or food boxes, visual design of device housings, wearable electronics, personal electronic devices, displays, detectors or sensors, vehicle interiors, antennas, tags, vehicle electronics, furniture, etc.

[0005] The multilayer structure can be obtained, for example, by using a substrate such as a circuit board or even a plastic film, which can be provided with the electronic device and can be overmolded by the plastic, so as to create a multilayer structure with the electronic device at least partially embedded in the molded layer. Thus, the electronic device can be hidden from the environment and protected from environmental conditions such as moisture, physical impact or dust, while the molded layer can also have various additional uses in terms of aesthetics, transmission medium, sizing, etc.

[0006] Electronic devices such as electronic components, integrated circuits (ICs), and conductors can typically be disposed on a substrate element by a variety of different techniques. For example, off-the-shelf electronic devices such as various surface mount devices (SMDs) can be mounted on the surface of a substrate that ultimately forms an internal or external interface layer of a multilayer structure. In addition, the technology that falls under the term "printed electronics" can be applied to directly and substantially additively produce electronic devices to an associated substrate. In this context, the term "printing" refers to various printing techniques that can produce electronic devices / electrical components from printed materials by substantially additive printing processes, including but not limited to screen printing, flexographic printing, and inkjet printing. The substrate used can be flexible, but this is not always the case.

[0007] Electronic components are used in a variety of different applications. In many of these applications, such as in many control systems or user interfaces that utilize electronics, sensors, switches, and / or devices for monitoring and / or for responding to changes in pressure affecting them, such as pressure sensors or mechanical buttons, are desirable features. Sensors may be based on monitoring capacitance, inductance, or resistance, or based on changes in optical properties or based on a variety of other known technologies. Devices that utilize sensors may have a variety of forms and may be used for different purposes and in different environments.

[0008] One example of a technical field in which mechanical buttons are utilized, for example, is the automotive industry. A vehicle may have various electronic devices connected to the vehicle's public power system. The devices are typically controlled by using devices that monitor the pressure affecting them and / or operate in response to changes in said pressure or by applying a force such as in the case of mechanical buttons. In addition, capacitive switches may be used as a means of controlling devices in a vehicle. However, under those conditions, capacitive contactless electrical switches are prone to erroneous functions caused by electromagnetic interference, or to erroneous detections by the capacitive sensor or its system, which are made in response to hand movements that are not intended to cause said detection or action of the capacitive sensor.

[0009] Typical mechanical buttons can also be used, however, they tend to be large, expensive and exposed to dirt such as grease from the user's fingers, and may otherwise adversely affect the elegant interior surfaces of the vehicle. When a mechanical button is integrated into a surrounding structure, the structure is designed so that the button can be arranged and fixed to the structure, and so that the button can be moved in response to pressure applied to the button. Typically, this is accomplished by separating the button or rotatable switch from the surrounding structure, for example, protruding from the structure or at least having a gap so that it can move relative to the structure. The button or switch can be laminated via a coating, or a separate protective layer can be arranged to cover the button or switch so as to protect them from dirt and provide a more uniform outer surface relative to the surrounding structure. The outer layer laminate or separate protective layer enables the button or switch to be used, that is, it is highly flexible in order to be able to operate the button or switch. However, the laminate or layer may be easily damaged or worn when repeatedly used. The laminate or layer may easily fall off from the button or switch, thereby degrading the performance of the device.

[0010] Therefore, there remains a need to develop methods for manufacturing pressure sensing switches and devices, and apparatus therefor, which are less susceptible to interference and more reliable in operation than known attempts. Summary of the invention

[0011] The object of the invention is to provide a method for manufacturing a strain gauge device, a strain gauge device and use thereof, a weighing device and a level indicator device. Another object of the invention is that the method facilitates the manufacture of the strain gauge device and that the strain gauge device is durable and reliable in operation.

[0012] The objects of the invention are achieved by a method, a strain gauge device and the use thereof, as well as a weighing device and a level indicator device as defined by embodiments of the invention.

[0013] According to a first aspect, a method for manufacturing a strain gauge device is provided. The method comprises obtaining a first substrate, preferably a first formable substrate film, for accommodating electronic components. The method further comprises printing the strain gauge device on the first substrate by a method of printed electronics, such as by screen printing or inkjet printing. The method further comprises molding a molding material layer, preferably by using injection molding, the molding material layer embedding the strain gauge device.

[0014] The method may include forming, such as hot forming or cold forming, the first substrate including the printed strain gauge device.

[0015] The method may comprise obtaining a second substrate, preferably a second formable substrate film, wherein moulding comprises moulding the layer of moulding material between the first substrate and the second substrate, such as between two substrate films.

[0016] The strain gauge device may be a first strain gauge device, and the method may include printing at least one second strain gauge device on the second substrate, at least partially at a location corresponding to the first strain gauge device.

[0017] At least one of the first substrate and the second substrate, such as a substrate film, may be flexible.

[0018] The method may comprise arranging a control unit for controlling operation of the strain gauge device on the first substrate or the second substrate and arranging electrical connections between the control unit and the strain gauge device by methods such as printed electronics. Moulding may preferably comprise moulding the layer of moulding material to embed the control unit.

[0019] The method may include arranging a capacitive sensing device, such as a capacitive sensing element of a capacitive sensor, on a first substrate and a second substrate.

[0020] The first substrate film may comprise a metal, preferably with a high resistivity, such as greater than or equal to 0.1 micro-ohm / m. The method may comprise providing an insulating layer on the first substrate, such as printing a dielectric layer using a dielectric ink, and printing the strain gauge device on the insulating layer.

[0021] According to a second aspect, there is provided a strain gauge device. The strain gauge device comprises a printed strain gauge device on a first substrate, such as on a substrate film, wherein the printed strain gauge device is embedded in a layer of molding material.

[0022] The strain gauge device may include at least three printed strain gauge devices, and the device may be configured to locate the pressure applied to the first substrate by triangulation based on the at least three printed strain gauge devices. The applied pressure mentioned herein refers to the deviation of the pressure at a certain point or area relative to the pressure in the surrounding area. This may be, for example, an increase in pressure due to a pushing motion of a user's finger over a small area.

[0023] The strain gauge apparatus may include a second substrate, such as a formable second substrate film, wherein a layer of molding material embedding the strain gauge device is arranged between the first substrate and the second substrate.

[0024] The strain gauge device may be a first strain gauge device on the first substrate, and the apparatus may include at least one second strain gauge device printed on the second substrate at least partially at a location corresponding to the first strain gauge device.

[0025] The strain gauge apparatus may include a control unit on the first substrate film or the second substrate film and arranged to be electrically connected to the strain gauge device.

[0026] A first substrate including a strain gauge device, such as a formable substrate film, may be formed into a three-dimensional (3D) shape.

[0027] The strain gauge device may be configured to function as a heating element.

[0028] At least the first substrate may be flexible.

[0029] The strain gauge device may also include a capacitive sensing device, such as including two capacitive sensing elements.

[0030] The strain gauge device may be configured such that the capacitive sensing device is configured to provide a first trigger signal and the resistance of the strain gauge device is configured to be monitored in response to the first trigger signal.

[0031] The strain gauge apparatus may be configured such that a resistance of the strain gauge device is configured to be monitored and provide a first trigger signal, and the capacitance sensing device is configured to be monitored in response to the first trigger signal.

[0032] The first substrate may include or consist essentially of one of the following materials: plastic, polymer, polycarbonate, polycarbonate-acrylonitrile butadiene styrene, poly(methyl methacrylate), polyimide, copolymer of methyl methacrylate and styrene monomer (MS resin), polyethylene terephthalate, wood, leather or fabric. According to various embodiments, the substrate may include or consist essentially of at least one natural and usually but not necessarily organically grown material selected from the group consisting of: wood, solid wood, veneer, plywood, stem bark, bark, birch bark, cork (including the cork layer of stem bark tissue), natural leather, and natural textile or fabric materials (which may be woven or knitted or otherwise produced from, for example, natural fibers), such as cotton, wool, linen, silk or the like.

[0033] The first substrate may include a metal, such as a thin metal layer, preferably with a high resistivity, such as greater than or equal to 0.1 micro-ohm / meter. The device may also include an insulating layer on the first substrate, such as a printed dielectric layer of a dielectric ink, and the printed strain gauge device may be on the insulating layer.

[0034] According to a third aspect, there is provided a hand-placement-removal detection sensor. The hand-placement-removal detection sensor comprises a strain gauge device according to the second aspect.

[0035] According to a fourth aspect, a steering wheel is provided, comprising the hand-placement-release detection sensor according to the third aspect.

[0036] According to a fifth aspect, there is provided use of a strain gauge device according to the second aspect in a hands-on-placement detection.

[0037] According to a sixth aspect, a weighing device is provided. The weighing device comprises a strain gauge device according to the second aspect.

[0038] According to a seventh aspect, there is provided use of a strain gauge device according to the second aspect for weighing.

[0039] According to an eighth aspect, there is provided a level indicator device.The level indicator device comprises a strain gauge device according to the second aspect.

[0040] According to a ninth aspect, there is provided use of a strain gauge device according to the second aspect for level indication.

[0041] The utility of the present invention arises from a number of issues depending on the implementation. Strain gauge devices can be easily manufactured by printing one or more strain gauges on a substrate. In addition, the strain gauge device and its characteristics, such as resistance value or resistivity, can be easily adjusted by using certain inks and / or by designing the geometry of the strain gauge device so that the desired characteristics are obtained. By molding a material layer on the strain gauge device or by molding a material layer to embed the strain gauge device, the strain gauge device is protected from environmental and interference effects, durable and reliable in operation. In addition, by utilizing a combination of printed strain gauge devices and molded material layers, mechanical coupling of the strain gauge device to the surface to which the force or pressure to be sensed as strain by the gauge device is to be applied is ensured. Moreover, in addition to the appropriate mechanical coupling, the molded material layer advantageously transmits force to the gauge device, thereby making the strain gauge device sensitive to force. Therefore, the present invention facilitates the manufacture of strain gauge devices having the above-mentioned characteristics and provides such an advantageous device.

[0042] The terms "first," "second," "third," etc. do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.

[0043] The exemplary embodiments of the present invention presented herein should not be interpreted as limiting the applicability of the appended claims. The verb "comprise" is used herein as an open-ended limitation, which does not exclude the existence of features that have not yet been recorded. Unless otherwise expressly stated, the features recorded in the dependent claims can be freely combined with each other.

[0044] The novel features which are believed to be characteristic of the invention are particularly set forth in the appended claims. The invention itself, however, both as to its construction and its method of operation and use, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In the figures of the accompanying drawings briefly described below, embodiments of the invention are shown by way of example and not limitation.

[0046] Figure 1 A flow chart showing a method according to an embodiment of the present invention is shown.

[0047] Figure 2 A strain gauge device according to an embodiment of the invention is schematically shown.

[0048] Figure 3 A strain gauge device according to an embodiment of the invention is schematically shown.

[0049] FIG. 4A to FIG. 4D Strain gauge devices according to various embodiments of the present invention are shown.

[0050] Figure 5 A strain gauge device according to an embodiment of the invention is schematically shown.

[0051] Figure 6 A strain gauge device according to an embodiment of the invention is schematically shown.

[0052] Figure 7 A strain gauge device according to an embodiment of the invention is schematically shown.

[0053] Fig. 8A and Figure 8B Examples of the operation of a strain gauge device according to various embodiments of the present invention are shown.

[0054] 9A to 9C A strain gauge device according to some embodiments of the invention is schematically illustrated.

[0055] FIG. 10A to FIG. 10C A strain gauge device according to some embodiments of the invention is schematically illustrated.

[0056] Fig.11Aand Fig. 11B A strain gauge device according to an embodiment of the invention is schematically shown.

[0057] Fig.12 A strain gauge device according to an embodiment of the invention is schematically shown.

[0058] Fig.13 A weighing device according to an embodiment of the invention is schematically shown.

[0059] Fig.14 A level indicator device according to an embodiment of the invention is schematically shown. DETAILED DESCRIPTION

[0060] Figure 1 A flow chart of a method according to an embodiment of the present invention is shown. In step 10, with reference to the startup phase, necessary tasks such as: materials; components, such as electrical contact pads, conductors, electronic devices and connectors; and tool selection, acquisition, calibration and other configurations can be performed. Special attention must be paid to the fact that the various components and material selections work together and survive the selected manufacturing process and the possible target product in which the structure or arrangement can be placed, which is naturally preferably pre-checked based on the manufacturing process specifications and component data sheets or, for example, by studying and testing the produced prototypes. Molding such as injection molding, in-mold decoration (IMD) / in-mold labeling (IML), lamination and / or printing equipment such as using screen printing or inkjet printing, etc., can therefore be raised to an operational state at this stage.

[0061] In step 11, a substrate such as for accommodating electronic devices can be obtained, preferably a formable substrate film or sheet. Optionally, before step 11 or in this step, decoration, graphic indication, color, etc. can be made on the film by, for example, printing. This can be omitted in the method flow or its position can be changed. Alternatively or additionally, other layers such as a protective layer can be provided with such features. For example, screen printing or inkjet printing can be applied. Decorative or indicative (for example, instructive) features can usually be provided using IMD / IML compatible methods. Ready-made substrate materials such as plastic film rolls can be obtained, and substrate materials can be optionally processed such as coating, coloring (if not initially the desired color or, for example, not initially the best transparency or translucency), engraving, embossing, forming, etc., or the substrate itself can be made indoors from scratch by molding such as injection molding, or other methods by the desired starting material.

[0062] In various embodiments, the substrate may be formable. The substrate may be substantially a formable material such as a thermoformable material, or at least include a formable layer. A first substrate, which may initially be substantially planar, e.g., sheet-like (extending considerably in the xy direction, while the thickness or z-dimension is small and substantially constant), may thus be formed using a suitable forming method such as thermoforming to exhibit a desired, at least partially three-dimensional (3D) shape (varying thickness, i.e., dimensional variation in the z direction) having, e.g., a protrusion or recess shape established before or during molding.

[0063] The material layers such as the first substrate and the optional second substrate can be processed and shaped according to the requirements set by each use scenario. They can exhibit a general shape such as a rectangle, a circle or a square. They can be substantially non-porous or contain recesses, notches, vias, cutouts or openings, optionally filled with other materials, for various purposes such as: attachment to other elements, conduction of electricity and, for example, related electrical power or other signals, assembly of electronic devices or other components, provision of channels or thinned portions for light or other radiation, fluids, etc.

[0064] The substrate and the plastic layer or potentially further layers (paint, ink, film, etc.) may be configured to exhibit a desired color or graphic pattern that may be externally perceptible. For example, an IML procedure may be utilized to arrange an embedded pattern in the structure.

[0065] Preferably, the formable substrate such as a film or sheet can be flexible. The substrate can include or be substantially composed of, for example, plastics / polymers such as polycarbonate (PC), polycarbonate / acrylonitrile butadiene styrene (PC / ABS), polymethyl methacrylate (PMMA), polyimide, copolymers of methyl methacrylate and styrene (MS resin), polyethylene terephthalate (PET) or metal. The substrate film or sheet can include organic or biological materials such as wood, leather or fabric, or any combination of these materials with each other or with plastics or polymers or metals. The substrate such as a film or sheet can also be further processed, such as formed, molded, coated, etc.

[0066] The substrate may include relief forms or shapes such as protrusions, ridges, grooves or recesses relative to the surface plane, optionally through holes. These features may be used to house or at least partially embed components such as conductors, electronic components, etc. in the substrate. Similar features may be present in the protective layer.

[0067] According to an embodiment of the present invention, at step 11, two preferably flexible substrates, such as films or sheets, may be obtained. The substrates may be similar or different relative to each other. One or both may be used to accommodate electronic devices, such as electronic components or conductors or conductive areas, such as patches or electronic contact pads. The substrates may be substantially two-dimensional or planar, such as sheet-like (naturally, with a finite thickness, however, relatively small in size relative to the other two dimensions forming the planar shape).

[0068] At step 12, one or more strain gauge devices may be printed on one or more substrates. This may require the use of any known printing method, such as screen printing or inkjet printing. The ink is advantageously a conductive ink, which may be transparent, or transparent to some extent, or opaque.

[0069] Regarding the properties of the conductive ink, it can be a composition comprising various materials such as one or more conductive materials and a binder material or a binder composition and a solvent (which evaporates under appropriate circumstances after printing). The conductive material can be, for example, silver, carbon or graphene. Polymer materials can be used as binders. The manufacture of strain gauges by printing provides advantages by using suitable conductive inks, that is, by adjusting the content of the ink so that the strain gauge device exhibits the desired properties during use, such as resistivity and / or changes in resistivity in response to strain. For example, the amounts of different conductive particles relative to each other can be adjusted. Alternatively or additionally, for example, the ratio of the amount of conductive particles to the amount of binder can be adjusted. By appropriately selecting the amounts, the electrical properties and / or mechanical properties of the ink can be adjusted as desired.

[0070] According to an embodiment of the present invention, the ink used is a soft ink material. By utilizing a soft ink material known to those skilled in the art, conductors are avoided, for example, making the structure itself more rigid, and thus making the strain gauge device less sensitive to deformation caused by the force or pressure directed onto the device. In step 12, one or more strain gauge devices and their elements, such as contact pads, traces, patches, coil-like structures or conductors, respectively, can be set, for example, by printing, at one or more desired positions on a substrate, such as one or more films or sheets, which is preferably flexible, and electronic components can be attached by appropriate mounting techniques. A flexible printed circuit (FPC) structure can thus be formed. Installation can, for example, include the use of adhesives, pastes and / or conductive inks to establish and stabilize the desired mechanical and electrical connections. Steps 11 and 12 can be performed repeatedly or alternately depending on the embodiment, so it is not always necessary or even impossible to separate them into dedicated execution stages.

[0071] The one or more strain gauge devices may preferably be conductive traces, patches or planar coils, such as comprising copper, metal mesh, indium tin oxide (ITO) or the like.

[0072] In optional step 13, forming, such as hot forming or cold forming, may be performed, for example by press forming or using vacuum or pressure. During forming, the preferably formable substrate, such as a flexible substrate film, may be formed into a desired substantially 3D shape using a mold structure. If some electronic components are already arranged on the substrate to be formed, they should preferably be arranged so that positions of maximum stress, such as positions of maximum pressure or curvature, are avoided during forming.

[0073] The molding may be performed after at least a portion of the circuit is disposed on the first substrate, so as to avoid or at least reduce a complex 3D assembly of the electronic device. The molding may still occur, for example as a separate processing step, before molding a plastic layer onto the substrate and the circuit disposed thereon using, for example, injection molding to at least partially overmold the substrate and the circuit disposed thereon. However, in some embodiments, the molding may be performed in conjunction with the molding. In order to facilitate or enhance such molding using, for example, a wooden substrate such as veneer or plywood, the substrate may be wetted first.

[0074] At step 14, a strain gauge device printed on a substrate such as one or more films may be arranged in a cavity defined by a mold structure. This may be accomplished by utilizing the mold structure and arranging substrates such as substrate films, if there are two, on opposite sides of the cavity of the mold structure, followed by preparing the mold structure for molding, such as by merging cavity plates or mold portions together to form a mold cavity. At 14, a preferred plastic layer is molded, preferably using injection molding techniques, the preferred plastic layer being, for example, a thermoplastic, thermoset, elastomeric material, polymer, organic, biomaterial, composite material such as organic or graphic, and any combination thereof. By molding a material layer over the strain gauge device, the following advantages are provided: the mechanical coupling of the strain gauge device to the mold material layer becomes strong and durable, and the mold material layer provides a good medium for transmitting force through the mold material to the strain gauge device (and being sensed as strain by a change in resistance of the gauge device).

[0075] In addition to other options, the molded layer can generally include an elastomeric resin. In more detail, the molded layer can include one or more thermoplastic materials, and the one or more thermoplastic materials include at least one material selected from the group consisting of: PC, PMMA, ABS, PET, nylon (PA, polyamide), PP (polypropylene), TPU (thermoplastic polyurethane), polystyrene (GPPS), TPSiV (thermoplastic silicone vulcanizate) and MS resin. In some embodiments, thermosetting materials can be used interchangeably or additionally with suitable molding methods such as reaction molding. For example, when a substrate such as one or more films has been arranged in a mold cavity and when the molding material is injected into the cavity by utilizing high pressure and then the substrate, i.e., one or two of them, is formed into one or more 3D shapes, step 13 and step 14 can also be performed substantially simultaneously.

[0076] At step 19, execution of the method ends. Once the molding material is sufficiently solidified, the manufactured strain gauge device can be removed from the mold structure. The solidification time period may be affected by, for example, the temperature of the molding material when it is injected. By printing onto a substrate and further molding the substrate, the strain gauge device is firmly secured (e.g., by pressing) to the structure undergoing stress and thus responds better than, for example, a post-laminated structure, especially in such a structure where the strain gauge device is positioned on a post-laminated panel component.

[0077] With respect to using conventional strain gauges, using printed strain gauges is particularly advantageous because the pressures caused by the molding process may be so high that conventional strain gauges are damaged or at least lose sensitivity to strain when the molding material surrounds and presses against the gauge. In addition, the strain gauge, especially when printed on a second substrate, on the side of the molding material layer opposite to the outer surface that is to receive the sensed pressure, is better mechanically coupled to the outer surface than if a separate plastic layer or laminate layer is used on top of the strain gauge. The better attachment provides the effect that pressure applied to the outer surface on the opposite side of the molding material layer is better transferred to the strain gauge through the molding material layer than if a laminate structure is used.

[0078] In various embodiments, the substrate may include or consist essentially of at least one natural and usually but not necessarily organically grown material selected from the group consisting of: wood, solid wood, veneer, plywood, stem bark, bark, birch bark, cork (including the cork layer of stem bark tissue), natural leather, and natural fabrics or fabric materials (which may be woven or knitted or otherwise produced by, for example, natural fibers), such as cotton, wool, linen, silk or the like. Clearly, in the case of reference to, for example, wood and veneer or plywood, some of the above options overlap and may appear simultaneously. In various embodiments, the first substrate does include or at least consists essentially of: organic matter, biological products, biological materials or the like, or any combination of these materials with each other and possible other materials, optionally carbon-based materials and / or various plastics. In the case of a wooden substrate, a paint layer or an additional molding material layer may be provided on the surface of the wooden substrate. In various embodiments of the present invention, an additional molding material layer may be provided on the various materials used in the substrate.

[0079] In various embodiments, the thickness of the first substrate or at least a sub-portion thereof, such as a wood, textile, leather or other organic natural base layer thereof, may be less than about a few (e.g., 2-6) millimeters, more preferably less than about 1 mm thick, even more preferably less than about 0.5 mm thick, and most preferably less than about 0.3 mm thick. In the case where the first substrate comprises, for example, a textile, leather or wooden layer such as veneer or plywood as described above, and at least one additional layer of, for example, a plastic material (e.g., a plastic film such as a thermoplastic film), the total thickness of the resulting substrate construction may still at least partially remain within the above range or slightly larger, typically up to one or two millimeters larger, depending on the thickness of the substrate. The functional characteristics of the strain gauge device may be affected by the nature of the ink used for printing (also as described previously herein), the geometry and / or size of the strain gauge device, the material of the substrate, the length, width and thickness of the conductors of the strain gauge device, and thus, as a combination of two or more of the above features, the resistance of the strain gauge device or the resistivity of a portion of the strain gauge device. The above features, alone or in combination, may also affect how the resistance of the strain gauge device changes with respect to the applied strain / pressure / force.

[0080] The strain gauge device may be used to sense pressure by coupling the terminals of the strain gauge device to a control unit such as a microcontroller, for example via an analog-to-digital (AD) converter, which may be a separate AD converter or converters, or included in the microcontroller. The microcontroller and / or the AD converter may be selected based on the properties of the strain gauge device, for example based on its resistance. On the other hand, the strain gauge device may be designed by taking into account the properties of the microcontroller and / or the AD converter used to operate the strain gauge device, for example, by making the strain gauge device have an appropriate geometry or size so as to match electrical parameters such as impedance, so that a separate amplifier may not be needed, but a simple microcontroller is sufficient to operate the strain gauge device.

[0081] One or more strain gauge devices may be used as a sensing device by utilizing an excitation voltage applied to the terminals of the strain gauge device. The excitation voltage may be applied by any suitable voltage source, such as one that produces an output voltage of 5V or 12V. The change in resistance may be sensed by, for example, a Wheatstone bridge configuration or any other suitable configuration for measuring an imbalance between a number of resistors in a configuration in order to measure a change in resistance of the strain gauge device.

[0082] The strain gage device of a strain gage apparatus according to embodiments of the present invention may be easily designed, for example by suitable dimensioning, to exhibit any resistance value and thus be used in conjunction with certain resistors included in a measurement configuration such as a Wheatstone bridge configuration.

[0083] Strain gauge devices can be used to sense pressure on a device by determining the gauge factor or gauge factor, which is the ratio of the relative change in electrical resistance to mechanical strain. According to embodiments of the present invention, a gauge factor of 0.01-0.2 - i.e., the gauge factor of the relative change in electrical resistance to mechanical strain - can be used to determine the presence of pressure on a device.

[0084] The measuring arrangement or system included in or arranged in connection with the strain gauge device may preferably include a control unit or microcontroller including at least one processing unit or processor. The control unit may be configured to measure the strain directed to the strain gauge device by an external object, such as a user's finger, or alternatively, the strain gauge device may be configured to measure the strain present in the structure and detect any change in the strain. The resistance value of the strain gauge device may be measured continuously, and if the device is used as a button or switch, an action may be performed if the resistance value exceeds or falls below a threshold value. In addition, the threshold value may need to be adjusted based on temperature or due to aging or "creep" of the strain gauge device and its resistance value. The resistance value and / or its change in response to strain may need to be calibrated regularly or randomly or when required. Alternatively or additionally, the operation of the device may be based on detecting transients in the resistance value by measuring. In addition, the transient may be characterized as a time domain or frequency domain model of a person's pressing action and compared with it. This may include defining in the model and accounting for the duration of the measurement signal for increased strain and / or certain slopes and / or durations of rising and / or falling edges for the measured resistance (ie, strain).

[0085] Figure 2 A strain gauge device 20 according to an embodiment of the present invention is schematically shown. First, a first substrate 21A such as a planar substrate for accommodating electronic components can be obtained at 201, which substrate can preferably be formable. The strain gauge device 22 can then be preferably arranged on the first substrate 21A by printing such as screen printing or inkjet printing. Next, at 202, it is shown that the strain gauge device 22 of the first substrate 21A accommodating the strain gauge device can be overmolded with a molding material layer 23 or the strain gauge device can be embedded in the molding material layer. This can be done by using a molding device such as injection molding. The other edges 27 of the molding material layer 23 can be defined, for example, by the structure of the molding cavity of the molding device or its mold.

[0086] Furthermore, a control unit 25, such as a microcontroller 25, may be arranged in electrical connection 26 with the strain gauge device 22, such as Figure 2 The microcontroller 25 can be arranged on the first substrate film 21A and thus also embedded in the molding material layer 23 , or embedded in some other location, for example externally relative to the molding material layer 23 .

[0087] The strain gauge device 20 according to various embodiments of the present invention may include more than one strain gauge device 22. The strain gauge devices 22 may be printed on the first substrate film 21A in parallel with each other. However, the strain gauge devices 22 may alternatively or additionally be arranged one on top of the other, such that one strain gauge device 22 is arranged on the first substrate film 21A, and the other strain gauge device 22 is printed on the one strain gauge device 22 by, for example, printing with an electrically insulating material between the other strain gauge device and the one strain gauge device. For example, the electrically insulating material is arranged by printing the electrically insulating material on the one strain gauge device 22 before printing the other strain gauge device 22 on the electrically insulating material at a portion corresponding to the one strain gauge device 22. Thus, there may be several strain gauge devices 22 at one location, which may be utilized individually to monitor strain or applied pressure / force at that location. Furthermore, recesses and protrusions may be utilized to direct forces to the strain gauge device 22 to be sensed as strain. In the case where the strain gauge device 22 is used as part of a button or switch, recesses and protrusions may be utilized to indicate, for example, the position of a button or slider. Furthermore, recesses and / or protrusions may be advantageous for visually impaired users.

[0088] According to various embodiments of the present invention, the strain gauge device 20 can be configured such that the magnitude of the strain measured by the strain gauge device 22 can be used to indicate, for example, the strength of a user command. Thus, the device 20 can be configured to, for example, control an actuator for moving a vehicle window upward and / or downward. The actuator can begin to lower or raise the window in response to the strain gauge device 20 sensing the applied pressure. However, the magnitude of the strain measured by the strain gauge device 20 can additionally be used to control the speed of lowering or raising the window. Thus, the presence of strain can be used as a switching command and the measured quantity to indicate the gain or strength of the action to be performed.

[0089] According to various embodiments of the present invention, the strain gauge device 22 may be used as a heating element. In these embodiments, the strain gauge device 22 should be designed to withstand the expected temperature values, or the power injected into the strain gauge device 22 to increase the temperature of the strain gauge device 22 should be kept low enough to avoid damaging the strain gauge device 22. The heating element may be used, for example, in a steering wheel, where the strain gauge device 22 is also used for hand-placement-off detection, i.e., for detecting when one or both hands of a user are actually placed on the steering wheel.

[0090] The resistance of the strain gauge device 22 may vary with temperature. According to embodiments of the invention, the effect of temperature on the resistance of the strain gauge device 22 may be compensated for by, for example, changing the level of the excitation voltage applied to the strain gauge device 22 based on the temperature affecting the strain gauge device 22. This may be implemented, for example, by configuring any of the microcontroller or AD converter or voltage source for providing the excitation voltage to adjust the excitation voltage of the strain gauge device 22 based on the temperature. According to embodiments of the invention, temperature compensation may be implemented by providing a reference resistor spaced a distance from the strain gauge device 22, preferably on the same or similar substrate on which the strain gauge device 22 is printed, and overmolding the reference resistor with a layer of molding material 23, the temperature behavior of the reference resistor thereby being inherently similar to the temperature behavior of the strain gauge device 22. This may then be used for temperature compensation of the strain gauge device 22. The reference resistor as described above may also itself be a strain gauge device 22. There may be one or several reference resistors that may be used for temperature compensation.

[0091] The effect of temperature on the strain gauge device 22 can also be used to develop a temperature sensor. This may require calibrating the resistance value at some reference temperature and then configuring a control system or control unit based on the temperature behavior of the strain gauge device 22 to determine the temperature that affects the strain gauge device 22. In addition, due to the strain / pressure / force changes in the resistance of the strain gauge device 22, it may be necessary to detect when a significant amount of pressure is applied to the strain gauge device 22 in order to provide an accurate temperature determination.

[0092] Depending on the embodiment, a separate temperature measurement may be used in the temperature compensation, such as measuring the ambient temperature and inputting the data into the control unit or a separate temperature compensation system.

[0093] On some substrates on which the strain gauge device 22 has been printed, the effect of temperature on the resistance of the strain gauge device 22 is substantially linear, at least within certain temperature ranges. However, in some substrates, the effect may also be non-linear. A control unit or temperature compensation system—for example, including a temperature measurement, a microcontroller, and an optional excitation voltage source—can be configured to provide a suitable compensation voltage relative to the substrate being used on which the strain gauge device 22 is to be or has been disposed.

[0094] It should be understood that temperature compensation and the use of strain gauge devices as heating elements or temperature sensors can also be used Figures 3 to 14 In the embodiment shown in .

[0095] Figure 3 A strain gauge device 20 according to an embodiment of the present invention is schematically shown. Figure 2At 301, which is substantially similar to 201 shown in FIG. , the substrate 21A containing the strain gauge device can be further formed, for example, by using a forming press or air pressure, such as hot forming or cold forming, vacuum forming, pressure forming or high pressure forming, to preferably have a 3D shape as shown at 302. At 303, it is shown that the strain gauge device 22 of the substrate 21A containing the strain gauge device can be overmolded with a molding material layer 23 or the strain gauge device can be embedded in the molding material layer. This can be done by using a molding device such as injection molding. The other edges 27 of the molding material layer 23 can be defined by the molding cavity of the molding device or the structure of its mold. It can be seen that the strain gauge device 20 exhibits a three-dimensional shape due to molding.

[0096] According to an embodiment of the present invention, the first substrate 21A or the second substrate 21B may preferably be a thin metal film or sheet. The strain gauge device 22 may be printed on such a metal film or sheet and may be overmolded using a molding material layer 23. However, an insulating layer may be advantageously provided, such as a dielectric layer printed on the first substrate using a dielectric ink, and then the strain gauge device 22 may be printed on the insulating layer. The strain gauge device 22 may be used to monitor, sense or detect pressure applied to a metal film or sheet, where, for example, a capacitive sensing device may not work properly due to the relatively high conductivity of the metal film or sheet. The metal film or sheet should preferably be configured to bend so that the strain gauge device 22 bends in response to the bending of the metal film or sheet. In some embodiments, the metal film or sheet may therefore need to be configured to bend when a user applies force, for example, through his / her fingers or arms. However, in some applications, the strain gauge device 22 may be used to monitor the deformation of the metal film or sheet, which should not be deformed under normal conditions, and may thereby provide an indication of damage to an object or device. According to one embodiment, the first substrate 21A is a metal, such as a metal film or sheet, and the strain gauge device 22 and optionally other electronic components are arranged to a second substrate 21B, such as a substrate film for housing electronics.

[0097] According to an embodiment, the first substrate film 21A and / or the further substrate films may comprise a metal, such as preferably a thin metal film or sheet, preferably having a high resistivity, such as higher than or equal to 0.1 micro-ohm / meter, which facilitates the operation of the strain gauge device 22 comprising a conductive ink.

[0098] According to embodiments of the present invention, there may be patterns disposed on the first substrate or additional substrates that may have a high dielectric constant or conductivity, and thus may be difficult to use a capacitive sensing device. In these applications, the use of a strain gauge device 20 according to embodiments of the present invention may be particularly advantageous.

[0099] FIG. 4A to FIG. 4D Strain gauge devices 22 according to various embodiments of the present invention are schematically shown. It can be seen that the strain gauge device 22 can be produced as a strain gauge device having a variety of shapes. FIG. 4A to FIG. 4D Only four embodiments are shown in the drawings, but it is clear that the strain gauge device 22 can exhibit some other shapes than those shown in the figures in question. The terminals of the strain gauge device 22 can preferably be connected to an electrical conductor 41, which can also be, for example, printed. In addition, there can be contact pads 42 for connecting the electrical conductor to the strain gauge device 22, for example by printing or other means. Figure 4A and Figure 4B A strain gauge device 22 is shown having a rectangular shape, and Figure 4C and Figure 4D The arc-shaped strain gauge device 22 is shown. It can be seen that the arc-shaped strain gauge devices 22 are different from each other in that: Figure 4C The conductive strips of the metering device 22 in the embodiment are similar to a sawtooth pattern, while Figure 4D The middle pattern includes arcs and connecting portions that form the metering device 22.

[0100] The geometry of the strain gauge device 20 may be selected so that false detection of applied pressure may be minimized or at least reduced. The molded material layer 23 may, for example, be made of two different parts and / or materials, or have a space between the two parts, so as to isolate different parts of the device from each other, thereby creating a pressure sensing area that can be monitored by different strain gauge devices 22 or groups of strain gauge devices 22.

[0101] Figure 5 A strain gauge device 20 according to an embodiment of the present invention is schematically shown. First, a first substrate 21A and a second substrate 21B such as planar substrates for housing electronic components may be obtained at 501, which may preferably be formable. The strain gauge device 22 may then be arranged on one of the substrates 21A, 21B. Next, at 502, it is shown that the strain gauge device 22 of the substrate housing the strain gauge device, in this particular case the first substrate film 21A, may be overmolded with the molding material layer 23 by molding a molding material layer 23 between the first substrate 21A and the second substrate 21B, or the strain gauge device may be embedded in the molding material layer. This may be accomplished by using a molding device such as injection molding. It should be noted that the strain gauge device 20 (device 20 including at least two strain gauge devices 22) may also be arranged on the second substrate 21B, alternatively or additionally.

[0102] Furthermore, at least one of the first substrate 21A and the second substrate 21B may include other electronic components 61, such as conductors, electronic devices, traces, pads, patches, etc. According to some embodiments, a control unit 25, such as a microcontroller 25, may be arranged on a different substrate relative to the strain gauge device 22. Then, the electrical connector 26 may extend through the molding material layer 23.

[0103] In various embodiments of the present invention, the first substrate 21A may be arranged at the outer edge of the device 20, which means that the pressure to be sensed by the device 20 is designed to be applied or intended to be directed from that side of the device 20, i.e. from the first side. Since temperature generally also affects the resistivity of the material, the strain gauge device 22 may also be affected by temperature changes as described earlier herein. Therefore, by arranging the strain gauge device 22 on the second substrate 21B, i.e. insulated from the first side of the device 20 by the molding material layer 23, the effect of temperature on the operation of the strain gauge device 22 on the first side may be minimized or at least reduced. The molding material layer 23 thus insulates the strain gauge device 22 from the ambient temperature or from the temperature of any object that is in contact with or in close proximity to the device 20, especially on the first side.

[0104] Figure 6 The strain gauge device 20 according to an embodiment of the present invention is schematically shown. Step 601 and Figure 5 The step 501 shown in is substantially similar. At 602, at least the substrate accommodating the strain gauge device can be formed, for example, by using a forming press or air pressure, such as hot forming or cold forming, vacuum forming, pressure forming or high pressure forming, to preferably have a three-dimensional shape. Preferably, both the first substrate 21A and the second substrate 21B can be formed at 602. At 603, it is shown that by molding a molding material layer 23 between the first substrate 21A and the second substrate 21B, the strain gauge device 22 of the substrate accommodating the strain gauge device can be overmolded with the molding material layer, or the strain gauge device is embedded in the molding material layer. This can be done by using a molding device such as injection molding. It can be seen that the strain gauge device 20 exhibits a three-dimensional shape due to molding. The control unit 25, such as a microcontroller 25, can be arranged on a different substrate relative to the strain gauge device 22. Then, the electrical connector 26 can extend through the molding material layer 23.

[0105] Considering material selection, the second substrate 21B can be substantially composed of at least one material selected from the group consisting of or including at least one material in the group consisting of: polymer, thermoplastic material, PMMA, PC, polyimide, MS resin, glass, PET, carbon fiber, organic material, biomaterial, leather, wood, textile, fabric, metal, etc. The material used can be at least partially conductive or more typically insulating. However, considering opacity / transparency, transmittance, etc., the optical properties can vary according to the embodiment.

[0106] Figure 7 A strain gauge device 20 according to an embodiment of the invention is schematically shown. Although the strain gauge device 22 has been provided, such as printed, on the second substrate 21B, the strain gauge device may also be provided on the first substrate 21A. The device 20 may also include a capacitive sensing device 70 including a first capacitive sensing element 71 and a second capacitive sensing element 72. The capacitive sensing elements 71, 72 may be, for example, planar conductive elements or "patches". According to Figure 7 In the embodiment shown in , the first capacitive sensing element 71, such as the Rx electrode, can be printed or arranged on the first substrate 21A as a ready-made component. The second capacitive sensing element 72, such as the Tx electrode, can be printed or arranged on the second substrate 21B as a ready-made component. The strain gauge device 22 can, for example, be arranged in parallel with the second capacitive sensing element 72, or if the second capacitive sensing element 72 has a closed shape such as a rectangle or a circle, it is arranged to be surrounded by the element 72. According to an embodiment of the present invention, the printed strain gauge device 22 can be used as an electrode of the capacitive sensing device. According to further embodiments, the capacitive sensing elements 71, 72 can be arranged to the same substrate or the same plane in parallel to one strain gauge device 22 or multiple strain gauge devices 22, that is, arranged to different positions, or arranged to different substrates and different positions, or aligned with the strain gauge device 22. In the case of using the strain gauge device 22 as part of the button, the capacitive sensing device 70 or at least its sensing elements 71, 72 can be arranged to the same button, even so that the strain gauge device 22 acts as one of the capacitive sensing elements 71, 72. Figure 7The strain gauge device 20 shown in or a similar type of device 20 can be used as a sensing device so that information from the capacitive sensing device 70 and the strain gauge device 20 can be used to detect an applied pressure or "touch". According to one embodiment, the measurement of the capacitive sensing device 70 can be used as a first trigger or to provide a first trigger signal, for example, when a first threshold is exceeded in the measurement or pressure sensing system. The system can be configured to start measuring the output of the strain gauge device 22 only after receiving the first trigger, so the strain gauge device 22 can be used to verify the measurement of the capacitive sensing device 70. Therefore, erroneous measurements of the capacitive sensing device 70 can be advantageously avoided by confirming the sensing of the strain gauge device 20. This is also advantageous because the strain gauge device 22 can remain passive and consume no electrical power as long as there is no first trigger sensed by the capacitive sensing device 70. According to another embodiment, the strain gauge device 22 can be used in the measurement or sensing system to sense or measure the first trigger, after which the capacitive sensing device 70 can be used to verify or confirm the measurement results of the strain gauge device 22. An intended action, for example due to pushing a certain button or at a certain location, may be performed only after both the capacitive sensing device 70 and the strain gauge device 22 indicate that there is a push, ie, sufficient pressure is applied.

[0107] According to an embodiment of the present invention, the capacitive sensing device 70 can be configured to determine the position of a user's hand or finger or the position of an object for causing the capacitive sensing device 70 to react. The determined position can then be used to activate the strain gauge device 22, i.e., the resistance of the strain gauge device 22 is measured based on the position determined by the capacitive sensing device 70, and the position of the hand or object is thus verified, and optionally the user has given a command. The system can then be configured to perform an action associated with such a command. For example, if multiple strain gauge devices 20 are arranged in the target device or system, only one or a portion of them can be activated based on the measurement of the capacitive sensing device 70. This has the advantage that the remaining or non-activated strain gauge devices 22, for example, do not consume electrical power. According to another embodiment, one or several strain gauge devices 22 can be arranged and configured to determine, for example, the position of a user's finger on a user interface, and then the capacitive sensing device 70 can be used to verify the position and / or receive a command from the user, for example, by a pushing motion.

[0108] Fig. 8A and Figure 8B An example of the operation of the strain gauge device 20 utilizing the strain gauge apparatus 22 and the capacitive sensing device 70 according to an embodiment of the present invention is shown in FIG.

[0109] exist Fig. 8AIn step 80A, with reference to the start-up phase, a strain gauge device 20 including at least one or several strain gauge devices 22 and one or several capacitive sensing devices 70 may be obtained and configured for use. In step 81A, the capacitive sensing devices 70 may be controlled, for example, by a control unit 25 connected to the strain gauge device 20, to sense whether the capacitance of one or more capacitive sensing devices 70 has changed, and if so, to determine the characteristics of the capacitance change. Then, in step 82A, the characteristics of the capacitance change may be used to determine the position or location of an object such as a user's finger. The position or location may be determined by known methods utilized in conjunction with capacitive sensors. Then, in step 83A, one or more strain gauge devices 22 at the determined position or location may be activated, for example, by the control unit 25 and / or an excitation voltage source, for measuring whether pressure is being sensed, i.e., whether the resistance of one or more strain gauge devices 22 has changed from its base value, or whether they will change during the time period in which the one or more gauge devices 22 are activated. If no pressure is detected in step 84A, the method may return to step 81A. On the other hand, if pressure is sensed at step 84A, measurements from one or more strain gauge devices 22 may be used, for example, to confirm the position or location determined by the capacitive sensing device 70. Thus, the capacitive sensing device 70 may be used to provide a first trigger signal, and the strain gauge device 22 may be activated in response to the first trigger signal, for example, to confirm the position determined by the capacitive sensing device 70, and optionally, at step 85A, the sensed pressure at the position or location may be configured to trigger a function or action, which may be, for example, any function configured for a particular device or system. Thus, a strain gauge device 20 such as that described herein may be used, for example, as a button or slider, or as any control device of the system in question suitable for triggering an action. Step 89A refers to the end of the method flow. Depending on the desired operation and use of the device 20, Fig. 8A The method may be performed once, continuously or intermittently.

[0110] Figure 8BAnother embodiment of the operation of the strain gauge device 20 is shown. Step 80B refers to a startup phase, in which a strain gauge device 20 including at least one strain gauge device or several strain gauge devices 22 and one or several capacitive sensing devices 70 can be obtained and configured for use. At step 81B, one strain gauge device 22 or preferably multiple strain gauge devices 22 can be activated, for example by the control unit 25, and their resistance is monitored. For example, step 82B can refer to comparing the resistance value or its change with a base value or threshold value. If no pressure is sensed, the method returns to step 81B. On the other hand, if pressure is sensed, then at step 83B, one or more capacitive sensing devices 70 at the corresponding position or location or area can be activated and its capacitance or their capacitance can be monitored. At step 84B, the position of the object causing the pressure, such as a user's finger, can be calculated based on the monitored capacitance. If the calculated position corresponds to the position of one or more strain gauge devices 22 that have sensed pressure, then at step 85B, the pressure can be sensed in accordance with the capacitance of the object. Fig. 8A The triggering function is triggered in a similar manner as described above. Step 89B indicates the end of the method flow. Depending on the desired operation and use of the device 20, Figure 8B The method may be performed once, continuously or intermittently.

[0111] According to yet another embodiment of the present invention, the strain gauge device 22 and the capacitive sensing device 70 of the strain gauge device 20 can be used or configured in parallel or simultaneously to monitor resistance or its change and capacitance, respectively. This may require activating both one or more strain gauge devices 22 and one or more capacitive sensing devices 70 at the same time and monitoring their relevant measurement parameters (e.g. resistance and capacitance). The measurements can then be used for cross-checking, or one of the measurements can be used to monitor environmental conditions, for example, and the other measurement can be used to receive pressure, i.e., commands from a user, for example. For example, the strain gauge device 22 can be used to monitor, for example, temperature or vibration, while the capacitive sensing device 70 can be used as a button or switch.

[0112] The combination of strain gauge device 20 and capacitance sensing device 70 may be configured to be operated by one control unit 25 or multiple control units 25. In case of a single control unit 25, the operation of the devices 20, 70 may be divided based on a time division method or a frequency division method.

[0113] By the methods described herein (particularly with respect to Figure 1) Manufacturing the structure including the strain gauge device 22 and the capacitive sensing device 70 described herein provides the following advantages: the structure can be manufactured in one process, thereby creating an efficient way to produce the structure and produce an integrated and durable structure including a pressure sensing device used as a sensor, button or switch. In addition, the capacitive sensing device 70 and the strain gauge device 20 can be configured to verify each other's measurements, such as by using a control unit 25, which includes at least a processor and other basic components known in the art.

[0114] Fig. 9A , Fig. 9B and Fig. 9C A strain gauge device 20 according to an embodiment of the present invention is schematically shown. Fig. 9A In the embodiment of the present invention, a molding material layer 23 has been produced by using two different materials. A first molding material 23A has been used in the portion of the device 20 where one strain gauge device 22 or a plurality of strain gauge devices 22 are located. The strain gauge device 22 may be overmolded or embedded in this first molding material 23A, or a further material layer may be provided between the strain gauge device 22 and the first molding material 23A. Other portions may have been molded with at least a second molding material 23B. The further material may be, for example, a relatively thin layer of the second molding material 23B. The first molding material 23A may preferably be softer than the second molding material 23B so that the strain gauge device 20 is more sensitive to pressure applied to the device at the strain gauge device 22, while the portion of the device 20 having the second molding material 23B may be less sensitive. For example, polyurethane may be used as the softer first material 23A, while the harder second material 23B may be a harder plastic. Furthermore, recesses or protrusions may be provided in the portion where the strain gauge device 22 is located.

[0115] Fig. 9B The device 20 is shown using a cross-sectional view about section AA. One strain gauge device 22 or multiple strain gauge devices 22 can be arranged, for example printed, on one or both of the first substrate 21A and the second substrate 21B. The device 20 is shown as exhibiting a planar or two-dimensional shape, however, it can also be formed to have a 3D shape. By arranging the strain gauge device 22 on the substrate that provides the "inner" surface, that is, the substrate on the opposite side of the molding material layer 23A and the molding material layer 23B is the substrate designed to apply the pressure to be measured, the effect of local temperature changes, such as temperature changes due to a person's finger, on the measurement of the strain gauge device 22 can be minimized or at least reduced because the molding material layer 23A and the molding material layer 23B insulate the strain gauge device 22 from local temperature changes, whether the temperature is increased or decreased. The pressure is still effectively transmitted through the molding material layer 23A and the molding material layer 23B and can be measured using the strain gauge device 22. Fig. 9B In the embodiment of the present invention, for example, the first substrate 21A can be considered to be located on the outer surface of the device 20, and therefore, it is designed to receive the pressure to be measured. In this case, the second substrate 21B can be considered to be located on the inner side of the device 20. It can be seen that the first molding material layer 23A can be preferably molded at the corresponding part of the device 20, such as the strain gauge device 22. The first molding material layer 23A basically extends from the first substrate 21A through the device 20.

[0116] Fig. 9C Another embodiment of the device 20 is shown with a cross-sectional view about section AA. In this case, Fig. 9C It can be seen that the first molding material layer 23A does not extend through the device 20, but only extends through a portion of the thickness of the device 20. The strain gauge device 22 can be printed onto the first substrate 21A or onto the second substrate 21B, or, for example, if the second molding material layer 23B has been molded in the first stage, the strain gauge device 22 can be arranged in the second stage on the bottom of the recess or hole in which the first molding material layer 23A is molded. Alternatively or additionally, Fig. 9C The strain gauge device 20 shown in FIG. 1 may be such that the first molding material layer 23A is omitted, i.e. the strain gauge devices 22 are arranged, for example, on the second substrate 21B, and the molding material layers 23, 23B may be thinner, i.e. at least locally less thick (shorter in the z-direction in the case of a planar substrate), at least at locations of the device 20 corresponding to the strain gauge device or devices 22. FIG. 10A to FIG. 10C From above or below ( Fig. 10A ) and according to the cross-sectional side view about section CC ( Fig. 10B and Fig. 10C ) schematically shows a strain gauge device 20 according to some embodiments of the present invention. The device 20 may include one or preferably multiple strain gauge devices 22 arranged to a ridge 28 or protrusion 28, or arranged to a recess (recess) 28 or hole 28. In the case of multiple strain gauge devices 22, the strain gauge device 20 can be configured to operate as a slider, for example, as a touch slider. Although multiple strain gauge devices 22 can be arranged on the surface of a planar substrate, and the device 20 is configured to operate as a slider, Fig. 10A Strain gauge devices 22 are shown arranged on ridges 28 or valleys 28. By having ridges 28 or valleys 28, forces causing strain are better transferred to the strain gauge device or devices 22. Fig. 10B An embodiment of the apparatus 20 is shown that includes one or more strain gauge devices 22 in a ridge 28 or protrusion 28 . Fig. 10C An embodiment of an apparatus 20 including one or more strain gauge devices 22 in a recess 28 , hole 28 , or groove 28 is shown.

[0117] Fig.11A and Fig. 11B Embodiments of the invention are schematically shown. Fig.11A A strain gauge apparatus 20 is shown comprising a plurality of strain gauge devices 22 arranged on substrates 21A, 21B. Fig.11A In an embodiment of the present invention, three parallel strain gauge devices 22, namely first strain gauge devices 22A, are arranged on the first substrate 21, preferably on the inner surface relative to the molding material layer 23 thereof and thus embedded in the molding material layer 23. In addition, another three parallel strain gauge devices 22B, namely second strain gauge devices 22B, may be arranged on the second substrate 21B, preferably on the inner surface thereof and thus embedded in the molding material layer 23. The strain gauge devices 22A, 22B of the first substrate 21 and the second substrate 21B may overlap, respectively, so that a portion of each strain gauge device 22 may be located at a portion of the device 20 corresponding to one or more strain gauge devices 22 on the opposite substrate, i.e., the first strain gauge device 22A is relative to the second strain gauge device 22B. At least one first strain gauge device 22A may be at least partially at a position corresponding to at least one second strain gauge device 22B. According to an embodiment, the strain gauge device 22B on the second substrate 21B may be arranged perpendicular to and overlapped with the strain gauge device 22A on the first substrate 21A as described above. According to an embodiment, by arranging the strain gauge devices 22A, 22B in a Fig.11A By overlapping the two layers in the manner described above, especially when printing with transparent ink, a touch screen can be obtained.

[0118] Fig.11A The configuration shown in can be used to locate an area to which pressure is being applied. This can be achieved by measuring the output of all six strain gauges 22A, 22B. The six strain gauges 22A, 22B essentially define or form nine areas or points, i.e., a matrix that can be used to detect pressure points. For example, if pressure is applied to the upper right corner of the surface of the device 20 including the strain gauges 22, the resistance change of the strain gauge 22A on the right side of the first substrate 21A is greater than the resistance of the other two strain gauges 22 on the first substrate 21A. In addition, since there are also strain gauges 22B on the second substrate 21B, the resistance change of the uppermost strain gauge 22B on the second substrate 21B is greater than the resistance of the other two strain gauges 22B on the second substrate 21B. Therefore, the pressure point can be located in the upper right corner of the device 20. It should be noted that the size of the matrix including such measurement points defined by the strain gauges 22A, 22B can have any size, for example, 2×2, such as Fig.11A3×3, or 3×4, or 4×4, etc. as shown in . Fig. 11B The cross-sectional view about section BB shows Fig.11A Device 20.

[0119] According to an embodiment, the first strain gauge device 22A and the second strain gauge device 22B may be arranged on the surface of substantially the same substrate, i.e., the first substrate 21A or the second substrate 21B. The first strain gauge device 22A may be printed on the first substrate 21A, then an electrically insulating material such as a dielectric layer may be printed on the first strain gauge device 22A, and then the second strain gauge device 22B may be printed on the dielectric layer, so that the dielectric layer electrically separates the first strain gauge device 22A and the second strain gauge device 22B from each other. An advantage of having multiple strain gauge devices 22 on top of one another at the same location is that the measurements of each strain gauge device 22 can be used to cross-check or verify the measurements of the gauge device 22. In addition, this allows self-correction for temperature or other stress creep or offset. According to a further embodiment, the strain gauge devices 22 arranged at the same location may be such that they are directionally sensitive. This means that one gauge device 22 may be more sensitive to the x-direction of the xy plane, while another strain gauge device is more sensitive to the y-direction of the xy plane. Additional directionally sensitive strain gauge devices 22 may also be arranged thereon.

[0120] According to some embodiments, the conductive ink used to print the strain gauge device 22; 22A, 22B may be transparent, which allows the production of touch screens in which the strain gauge device 22; 22A, 22B is used to sense the presence and location of a touch. However, according to another embodiment, the ink used may be opaque.

[0121] Fig.12 A further embodiment of the present invention is shown. There may be at least three strain gauge devices 22 printed onto the substrate 21A, 21B substantially in one plane, wherein the three strain gauge devices 22 substantially define the three vertices of an imaginary triangle. Such a configuration may then be used in a triangulation process when locating the point at which pressure is applied. In this case, Fig.12The pressure point P in is on the triangular area defined by the strain gauge devices 22. The applied pressure mentioned in this article refers to the deviation of the pressure at a certain point or area relative to the pressure in the surrounding area. This can be, for example, an increase in pressure due to a pushing movement of the user's finger on a small area. By comparing the changes in the resistance of the three strain gauge devices 22 relative to each other, the distance of the pressure point P from each strain gauge device 22 can be determined. If the strain gauge devices or at least the resistance values ​​or their changes in response to strain / pressure / force are inconsistent, this may require calibration of the base value of the strain gauge device relative to each strain gauge device 22. It will be obvious to the skilled person that the number of strain gauge devices 22 can be more than three.

[0122] Injection molding can be applied in the manufacturing process. The substrate and optional protective layer (if already present) can be used as an insert in the mold structure or mold. Optionally, multiple injection molding or multi-component molding is applied to provide multiple materials, for example, to a multilayer structure. The plastic layer can be at least partially optically transparent and / or include recesses or through holes to provide a visual path to the electronic device below, which may include optoelectronic components (light emitting diodes (LEDs), photosensitive detectors) or, for example, displays such as OLED (organic LED) displays. The plastic layer may additionally or alternatively include opaque, for example colored or graphic or translucent parts. The plastic layer may also be provided with surface relief forms or other features for various purposes, such as for optical purposes (e.g., light incoupling, outcoupling, scattering or reflection).

[0123] According to some embodiments, additional layers may also be laminated onto the molding material layer 23 or onto at least one of the substrates 21A, 21B, for example after molding, such as by using an adhesive, depending on the specific embodiment and / or the intended use of the resulting device 20 .

[0124] The best process parameters should be known in advance or determined by field tests by a person skilled in the art according to the materials, dimensions and components used. Only a few exemplary guidelines can be given for general guidelines. When the substrate is PET and the plastic to be overmolded thereon is PC, the temperature of the melted PC may be between 280 degrees Celsius and 320 degrees Celsius, and the applicable mold temperature may be in the range of about 20 degrees Celsius to 95 degrees Celsius, i.e., for example, it may be about 80 degrees Celsius. The substrate 21A, 21B such as a film and the process parameters used should be selected so that the substrate remains substantially solid during the process.

[0125] Potentially pre-installed electronics are preferably already attached to the substrate so that they remain immobile during molding. Optionally, roll-to-roll technology can be utilized during the execution of the manufacturing method at least for selected stages, such as providing traces / components for the substrate or integrating layers together. Roll-to-roll applications require some flexibility from the material layers used. Therefore, the final product (the device obtained) can be flexible. However, the invention is actually also applicable to scenarios with more rigid sheets of material or generally desired pieces of material.

[0126] Target electronic products or devices 20 incorporating one or more strain gauge devices 22 may include, for example, consumer electronic devices, industrial electronic devices, automation equipment, mechanical devices, automotive products, safety or protection equipment, computers, tablets, tablet phones, mobile terminals such as mobile phones, alarm devices, wearable electronic devices / products (clothing, headwear, footwear, etc.), sensor devices, measurement devices, display devices, game controllers or consoles, lighting devices, multimedia or audio players, audio-visual (AV) equipment, sports equipment, communication equipment, transportation or carrying equipment, batteries, optical devices, solar panels or solar energy devices, transmitters, receivers, wireless control devices or controller devices.

[0127] According to one example scenario, a strain gauge device 20 according to an embodiment of the present invention may be used to detect when a user's hand is placed on a steering wheel of a vehicle, i.e., for hand-placement-off detection and / or for use in a hand-placement-off detection sensor. This may be achieved by the device 20 including a strain gauge device 22, which may be used to detect the pressure applied to the steering wheel by the user's hand.

[0128] According to another embodiment, when a capacitive sensing device 70, such as a capacitive sensor, is arranged to the device 20 in addition to the strain gauge device 22, the strain gauge device 22 can be used as a second trigger or provide or generate a second trigger signal, for example if a second threshold value related to the measured resistance value is exceeded, in order to verify that the capacitive sensing device 70 correctly indicates the presence of a hand on the steering wheel. The strain gauge device 22 according to various embodiments of the present invention can be advantageously used in applications where the capacitive sensing device 70 is prone to errors due to interference from power equipment, etc. or, for example, false detection of a nearby user's hand or false detection due to drops or dirt. In the automotive industry, reliability related to sensor operation is an important safety issue.

[0129] The strain gauge device 20 can be advantageously used as a sensing device, for example in the case of a touch screen or control equipment such as a steering wheel or any user interface, which firstly senses the pressure being applied to the device and / or secondly, can choose to perform different actions depending on the magnitude of the force applied. The strain gauge device 20 according to an embodiment of the present invention is insensitive to the fact that the user's hand is dry or wet, because the device 20 operates at least in part based on the following force or pressure: the force or pressure is generated by the user or any object and transmitted to the strain gauge device 22 and sensed as strain (by measuring the resistance of the gauge device 22 or the change of its resistance value).

[0130] Embodiments of the strain gauge device 20 may be used for weighing in a variety of applications. The strain gauge device 20 may be advantageously arranged to a weighing device 110, such as Fig.13 . The strain gauge device 22 and the measurement system associated with the strain gauge device 20 can be configured to provide a measurement signal about the weight (or force due to the mass of gravity) of an object placed on the weighing device 110. The strain gauge device 20 can be arranged on a surface 112, which is arranged for placing the object to be weighed, or there can be an additional surface or structure on which the object is to be placed, and then the pressure (or force) is transmitted to the strain gauge device 22. The strain gauge device 20 for weighing or weighing device 110 can be manufactured at least in part by utilizing an embodiment of the manufacturing method described previously herein. The weighing device 110 can preferably include a digital screen 111 for presenting the weighing result to the user. The screen 111 can preferably be connected to a control unit 25, which includes at least a processor and a device for determining a change in the resistance value of the strain gauge device 22 for calculating the weight (or mass) of the object placed on the weighing device 110. There can also be a user interface, such as a button 113 included in the weighing device 110.

[0131] Embodiments of the strain gauge device 20 may be used for level, such as liquid level 121 indication in various applications. The strain gauge device 20 may advantageously be arranged to a level, such as liquid level, indicator device 120, such as in the form of a strip comprising one or more strain gauge devices 22 or one or more strain gauge devices 20. The strain gauge device 22 and a measurement system connected to the strain gauge device 22, such as a control unit 25, may be configured to provide a measurement signal relative to the level of a quantity to be measured, such as a liquid level 121. There may be one or several strain gauge devices 20, such as arranged, for example, on the inner wall of a container containing a liquid. Fig.12 According to an embodiment, there may be several strain gauge devices 22 of the strain gauge apparatus 20 that can be arranged in the strip, such as Fig.14. The strip may be arranged, for example, on the inside wall of a container, and thus the strip may be used to indicate the liquid level, because the liquid exerts a static force on the strain gauge device 22 below the liquid surface 122B, while the air or atmospheric pressure affects the strain gauge device 22 on the surface 122A. It should be noted that the strain gauge device 20 may also be used as a level indicator (device) other than for liquids, for example for sand or other such granular materials. The strain gauge device 20 for level indication or for use in a level indicator may be manufactured by utilizing embodiments of the manufacturing method described previously herein.

[0132] Strain gauge devices 20 according to various embodiments of the present invention may be used in a variety of applications, some of which are set forth above. However, in general, one or more strain gauge devices 22 according to the present invention may be provided by printing on a variety of different substrates or surfaces and then used in any suitable device or system. The substrate may be rigid or formable or flexible. Furthermore, the substrate may be planar or exhibit a significant thickness. In addition to what has been set forth above, strain gauge devices 20 according to various embodiments of the present invention may be used, for example, in vehicles, such as in car seats (to detect whether someone is sitting in the seat and / or for heating), in turn signal switches, in gear levers, or in any switch for controlling devices in the vehicle such as windows or lighting. Furthermore, it should be understood that strain gauge devices 20 according to embodiments of the present invention may be used in other fields besides vehicles, such as with respect to Fig.13 and Fig.14 In general, the strain gauge device 20 may be used as a sensor, for example, for monitoring a parameter and / or as a switch to operate an actuator in any suitable system.

[0133] Features described in the foregoing description may be used in combinations different from those explicitly described. Although functions have been described with reference to certain features, these functions may be performed by other features whether described or not. Although features have been described with reference to certain embodiments, these features may also be present in other embodiments whether described or not.

Claims

1. A method for manufacturing a strain gauge device, the method comprising: obtaining a first substrate for accommodating electronic components, the first substrate comprising a first formable substrate film, printing a strain gauge device onto the first substrate by a printed electronics method, and A layer of molding material is injection molded over the strain gauge device, thereby embedding the strain gauge device in the layer of molding material.

2. A strain gauge device comprising: A printed strain gauge device on a first formable substrate film, the strain gauge device being embedded in an injection molded material layer, wherein the first formable substrate film comprises at least one of the following: plastic, polymer, polycarbonate, polycarbonate-acrylonitrile butadiene styrene, poly(methyl methacrylate), polyimide, copolymer of methyl methacrylate and styrene monomer (MS resin), polyethylene terephthalate, wood, leather or fabric.

3. A hand-placement-removal detection sensor comprising the strain gauge device according to claim 2.

4. A steering wheel comprising the hands-placement-release detection sensor according to claim 3.

5. A method for using a strain gauge device according to claim 2, comprising providing hand-placement-release detection.

6. A weighing device comprising a strain gauge device according to claim 2.

7. A method for using a strain gage apparatus according to claim 2, comprising performing weighing using the strain gage device.

8. A level indicator device comprising a strain gauge device according to claim 2.

9. A strain gauge device comprising: At least three printed strain gauge devices on a formable substrate film, the at least three strain gauge devices being embedded in a layer of injection molded material, wherein the apparatus is configured to locate a pressure applied to the formable substrate film by triangulation based on the at least three printed strain gauge devices.

10. A strain gauge device comprising: a printed strain gauge device on a first formable substrate film, wherein the strain gauge device is embedded in a layer of injection molded material; and A second formable substrate film, wherein a layer of molding material embedding the strain gauge device is arranged between the first formable substrate film and the second formable substrate film.

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