CN112558807A

CN112558807A - Intelligent surface

Info

Publication number: CN112558807A
Application number: CN202011261612.8A
Authority: CN
Inventors: 周幼宁; 西尔瓦诺·弗兰
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-11-12
Filing date: 2020-11-12
Publication date: 2021-03-26

Abstract

The invention relates to a smart surface for detecting the position and/or pressure of at least one touch, comprising: a support substrate (1100); a deformable light guide (1200) positioned over the support substrate (1100), the deformable light guide (1200) for transmitting the sensed light; a cover layer (2500) over the deformable light guide (1200); and an intermediate layer (3600) located between the deformable light guide (1200) and the cover layer (2500).

Description

Intelligent surface

Technical Field

The present invention relates to an intelligent surface for detecting the position and/or pressure of at least one touch.

Background

Smart surfaces refer to surfaces made of different materials, textures, and geometries that have haptic functionality embedded to enable user interaction and gesture recognition with the smart surface. The functionality provided by a cell phone/tablet through a rigid surface traditionally made of glass or pointing operations provided by a touch pad on a plastic/glass surface in a laptop/notebook computer can be considered an intelligent surface.

In general, a smart surface is a system consisting of a sensor that senses a touch input from a user and a control unit that processes the touch input. In contrast to common touch digitizers (e.g., touch screens and touch pads) that require a determination of whether a touch event is present across an area, the smart surface can selectively respond in a particular area with different sensitivity, resolution, and reporting rate, and it can be configured to accommodate different applications.

The portion of the smart surface used as a touch digitizer typically contains a touch sensitive medium and, in some cases, an overlay. Touch sensitive media may use a variety of technologies including capacitive, resistive, optical FTIR, and Surface Acoustic Wave (SAW).

Another known touch sensitive medium for detecting touch is a deformable light guide, which is a deformable structure that confines light so that it can behave like an electromagnetic wave and transport or guide it from one source to another. Fig. 1A and 1B schematically show such a touch sensor 1000 according to the prior art. As shown in fig. 1A, touch sensor 1000 includes a deformable light guide 1200 placed on a support substrate 1100 and at least partially surrounded by a light emitter 1300 and a receiver 1400. As can be seen in fig. 1B, the application of pressure P1 causes the deformable light guide 1200 to change shape, for example by a finger, not shown. This change in shape changes the amount of light received by the receiver 1400, as schematically illustrated by ray R1, ray R1 escaping from the touch sensor 1000, thereby reducing the amount of light received by the receiver 1400. Such a touch sensor is a known method, as described in document WO 2013/168127. You can find more description in this file.

For some known touch sensing technologies (e.g., optical FTIR touch and SAW), the touch sensing medium may also be used as a cover layer. In contrast, capacitive and resistive may have an overlay layer that is separate from the touch sensitive medium. In both cases, these touch technologies require intimate contact between the touch sensitive medium and the cover layer for best results. This is because discontinuities in the interface between the touch sensitive medium and the cover layer will severely affect the uniformity and performance of the touch sensing operation. For example, a defect in a sense trace in a capacitive touch layer will severely affect its impedance, resulting in a distorted measured capacitance. Defects in the SAW that do not match uniformly between the touch sensitive medium and the cover layer can cause acoustic scattering, thereby affecting touch location. Thus, in those technologies that allow or require a cover layer on top of the touch sensitive medium, it is often required that these elements are connected to each other in a stable manner.

On the other hand, in some typical applications of smart surfaces, such close contact between the touch sensitive medium and the cover layer is disadvantageous. In particular, some materials that may be used as a covering for a decorative surface (e.g., wood veneers, leather, or textiles) may not be flat in themselves. In certain other cases, for example to reduce costs, the covering may comprise a thin layer of expensive material, such as leather or wood, which must be attached to an additional backing layer to enhance its mechanical strength properties and/or to facilitate some other processing. Even if the thin layer is sufficiently uniform and planar, the backing layer can introduce problems with non-uniform and non-planar surface characteristics.

In technologies that require bonding of an overlay layer to a touch sensitive medium, such as Force Scale Resistive (Force Scale resist) sensors, the presence of uneven surfaces or surface roughness can cause a number of problems. In particular, where bonded to the touch sensitive medium, the cover layer typically faces the touch sensitive medium with an uneven surface. They are usually bonded by resin glues or by thermoplastic curing. In this way, the gaps and ridges of the uneven surface are filled with resin, which changes the compliance of the surface, making it harder. The effect of such adhesion will be a hardening of the cover layer and will impair the conduction of local deformations by the touch sensitive medium, which may lead to a reduction of the touch sensitivity.

For touch sensors based on locally confined/compressed deformation-producing light guide sensing mechanisms, such as those shown in fig. 1A and 1B, such a touch sensitive medium-to-cover layer bonding process is not required. However, this technique is also affected by surface roughness.

Here, fig. 2A schematically shows a smart surface 2000 according to the prior art, while fig. 2B schematically shows an enlargement of a part of fig. 2A S1. The smart surface 2000 is based on the touch sensor 1000 and differs from the smart sensor 1000 due to the presence of the overlay 2500. As shown in FIG. 2B, the cover layer 2500 generally includes an outer surface 2510 and an inner surface 2520. the surface of the outer surface 2510 that is contacted by a user. Inner surface 2520 acts as a touch sensitive medium, which will face deformable light guide 1200. The two surfaces are schematically shown as being bounded by one another by a cut line. It will be clear that the figures are intended to be schematic representations only, and that in fact a plurality of layers may be included in the top cladding layer 2500. For the purpose of describing the problems faced by the art, the drawings are intended to illustrate the presence of roughness on the inner surface 2520, as shown in fig. 2B.

Fig. 2C schematically shows the smart surface 2000 under the influence of a pressure P1. Similar to fig. 1B, the smart surface 2000 generally compressively deforms under the force applied by pressure P1. However, the presence of the cover layer 2500, particularly the roughness on the inner surface of 2520, results in a number of possible reaction behaviors of the smart surface 2000 to the pressure P1, affecting how the deformable light guide measures the pressure P1.

Fig. 2D and 2E schematically show an enlarged portion S2 of fig. 2C, having two configurations of the material of the smart surface 2000, respectively: a first configuration and a second configuration. In particular, in the first configuration, the material of the inner surface 2520 is softer than the material of the deformable light guide 1200, while in the second configuration, the material of the inner surface 2520 is harder than the material of the deformable light guide 1200.

As shown in fig. 2D, if the material of the inner surface 2520 is softer than the material of the deformable light guide 1200, the inner surface 2520 will tend to be compressed. This causes deformation of the surface topology, which will have an effect on the sensing characteristics of the deformable light guide 1200, as it changes the shape of the interface between the deformable light guide 1200 and the inner surface 2520 and the material, such as air, between them. The change in the sensing characteristics of the deformable light guide 1200 will further depend on the particular characteristics of the inner surface 2520, such as the surface topology and roughness. Since the inner surface 2520 may be a material such as leather or wood, which itself exhibits some property variation of its own, it would be very complicated to compensate for the change in the sensing properties of the deformable light guide 1200 in a predetermined manner.

On the other hand, as shown in FIG. 2E, if the material of the inner surface 2520 is harder than the material of the deformable light guide 1200, the deformable light guide 1200 will tend to deform. However, while the large range of deformation of the deformable light guide 1200 is a function of the pressure P1, the small range of deformation shown in fig. 2E is a function of the particular characteristics (e.g., surface topology and roughness) of the inner surface of 2520. The shape change uncertainty variable of the deformable light guide 1200 will also affect the sensing characteristics of the deformable light guide 1200. Furthermore, in this case, since the uncertain variable is caused by the specific characteristics of a given material of the inner surface of 2520, it becomes complicated to compensate for it.

The present invention will present a method that overcomes one or more of the problems identified above.

In particular, it is an object of the present invention to provide a smart surface based on a deformable light guide 1200 that can work reliably, providing accurate position and pressure information, when used with an inner surface 2520 material having variable properties such as topology, roughness, stiffness, etc.

Disclosure of Invention

The inventors have realised that the above problems can generally be solved by introducing an intermediate layer with controllable properties between the deformable light guide and the inner surface.

In particular, because of the presence of such intermediate layers of known properties, we can choose surface layers and deformable light guides of different properties. By choosing an intermediate layer of suitable controllable properties, the deformable light guide can be operated normally even in the case of surface layers of different properties and deformable light guides.

In particular, embodiments of the present invention may relate to an intelligent surface for detecting the position and/or pressure of at least one touch. This intelligent surface includes: a support substrate, a deformable light guide, a cover layer, and an intermediate layer; a deformable light guide located above the support substrate through which sensing light is transmitted, where sensing light refers to near infrared light emitted by the emitter for sensing deformations in the deformable light guide, and then recorded by the receiver; a cover layer over the deformable light guide; an intermediate layer is located intermediate the cover layer and the deformable light guide.

Due to the existence of the intermediate layer, the characteristics of the intermediate layer can be effectively controlled, so that the covering layer with various different characteristics can be selected.

In some implementations, the intermediate layer can have an arithmetic average roughness greater than twice the wavelength of the sensing light.

Due to this approach, diffraction effects that complicate or distort the retrieval of pressure information can be avoided. Furthermore, the post-processing of the signals received by the receiver can be greatly simplified.

In some implementations, the intermediate layer can at least partially absorb the wavelength of the sensing light.

Due to this approach, the attenuation loss of the sensed light can be increased when there is pressure on the smart surface, thereby making it easier to detect a touch on the smart surface.

In some implementations, the attenuation loss of the intermediate layer may be at least twice the attenuation loss of the deformable light guide. This may further increase the attenuation loss of the sensed light when there is pressure on the smart surface, making it easier to detect a touch on the smart surface.

In some embodiments, the intermediate layer comprises voids that can be filled with a substance such as air, glue, oil, or other medium, wherein the refractive index of the filled substance divided by the refractive index of the material of the deformable light guide is less than 1; preferably, the value of the refractive index of the substance divided by the refractive index of the material of the deformable light guide (1200) is less than 0.8; even smaller, such as a value of the refractive index of the substance divided by the refractive index of the material of the deformable light guide (1200) is less than 0.75.

In this way, we can obtain all internal reflections in the deformable light guide, which in the absence of touch increases the light refraction and transport in the deformable light guide.

In some embodiments, the middle layer may include a wire mesh between 0.1mm and 1.2mm in diameter, which may cross in multiple directions and have a regular or irregular spacing pattern.

In some embodiments, the intermediate layer may comprise a fabric.

Thus, we can select an interlayer that has certain characteristics including, but not limited to, arithmetic mean roughness.

In some embodiments, the fabric may include warp yarns and weft yarns, the warp yarns having a first diameter, the first diameter being in a size range between 0.1mm and 1.2 mm; preferably, the first diameter ranges in size between 0.5mm and 1 mm; and/or, the weft thread may have a second diameter, the size of the second diameter ranging between 0.1mm and 1.2mm, preferably, the size of the second diameter ranges between 0.5mm and 1 mm.

In this way we can best select the properties of the intermediate layer depending on the materials used in the deformable light guide and/or the combination of sensing light used.

In some embodiments, the fabric may comprise warp and weft, wherein the first angle of the weft relative to the horizontal may be greater than 6 degrees, preferably greater than 30 degrees, and/or wherein the warp is greater than 6 degrees, preferably greater than 30 degrees, relative to the horizontal.

In this way we can best select the properties of the intermediate layer depending on the commonly used elastomeric materials and/or sensing light combinations used in the deformable light guide.

In some embodiments, the fabric may include warp and weft threads, and the adjacent warp thread distance may have a distance between 0.5mm and 3mm, and/or the adjacent weft thread distance may have a distance between 0.5mm and 3 mm.

In some embodiments, the fabric may include warp yarns and weft yarns, the warp yarns may have a first diameter and the weft yarns may have a second diameter, a first distance between adjacent warp yarns and a second distance between adjacent weft yarns, the first distance and/or the second distance may be greater than [ (d1+ d2)/2+2 x λ ], wherein:

d1 is the first diameter;

d2 is the second diameter;

λ is the wavelength of the sensing light.

Drawings

FIG. 1A is a schematic view; a prior art touch sensor schematic;

FIG. 1B is a schematic view; the working principle of the touch sensor in the prior art is schematic;

FIG. 2A is a schematic view; a prior art smart surface schematic;

FIG. 2B is a schematic view; FIG. 2A S1 is an enlarged schematic view of a portion thereof;

FIG. 2C is a schematic view; a schematic diagram of a smart surface under pressure;

FIG. 2D is a schematic representation; topological deformation of smart surfaces-the inner surface material is softer than the light guide material;

FIG. 2E is; topological deformation of smart surfaces-schematic of inner surface material harder than light guide material;

FIG. 3 is a schematic view; a schematic of the smart surface of the invention;

FIG. 4A is a schematic view; top view of possible implementation cases of the intermediate layer;

FIG. 4B is a schematic view; top views of possible embodiments of the intermediate layer;

FIG. 4C is a schematic view; weft cut cross-sectional views of possible embodiments of the intermediate layer;

FIG. 4D is; the part S3 of FIG. 4C is an enlarged schematic view;

FIG. 5 is a schematic view; schematic top view of the fabric.

Description of reference numerals:

1000: touch sensor

1100: supporting substrate

1200: deformable light guide

1300: emitter

1400: receiver with a plurality of receivers

P1: pressure of

R1: ray of radiation

2000: smart surface

2500: covering layer

2510: outer surface

2520: inner surface

3000: smart surface

3600: intermediate layer

4400: wire mesh

4410: vertical line

4420: horizontal line

4440: voids

4600: first fabric

4610: warp yarn

4620: weft yarn

4630: angle of rotation

5600: second fabric

5610: first wire

5611: second wire

5620: third wire

5621: fourth line

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

The main characteristic of an uneven covering or backing layer is its surface roughness. A common parameter for evaluating surface roughness is the arithmetic mean roughness. In the following description, when the term roughness is used, arithmetic mean roughness is meant.

Hereinafter, whenever the term sensing light is used, it is intended to mean light that is transmitted and refracted in the deformable light guide for the purpose of sensing pressure or/and touch position.

Fig. 3 schematically illustrates a cross-sectional view of a central portion of a smart surface 3000 according to one embodiment. Here, the term center is intended to be opposite the periphery and should not be interpreted to mean the exact geometric center of the smart surface. Here, the term "periphery" generally defines an outer boundary region of the sensing region of the smart surface 3000, an edge of the smart surface 3000, or a region adjacent to the smart surface 3000.

The smart surface 3000, which generally allows for the detection of at least one touch or/and pressure, or may simultaneously detect the presence of multiple touches or/and pressures, includes a support substrate 1100, a deformable light guide 1200 positioned over the support substrate 1100, and a cover layer 2500 over the deformable light guide 1200.

The substrate 1100 is generally intended to provide rigid support for the smart surface 3000, and thus, we will select a material that can withstand at least the maximum pressure that the smart surface 3000 is rated to withstand without significant deformation.

In some embodiments, no significant deformation occurs meaning that the deformation along the vertical direction at any given point is less than 10% on the surface of the substrate 1100 facing the deformable light guide 1200, and more preferably less than 1% in any direction perpendicular to the deformable light guide 1200. In this context, the term "perpendicular" relates to the direction shown in the drawings, i.e. the direction substantially perpendicular to the smart surface.

In some other embodiments, the substrate 1100 has less than 10 a without significant deformation^-8A bending stiffness of 1/(N mm2), more preferably less than 10^-9A bending stiffness of 1/(N × mm 2). In some implementations, these values can be related to the stiffness of the substrate 1100, while in other implementations, they can be related to the stiffness of the smart surface structure 3000.

Bending stiffness refers to a parameter of deformation of the intermediate layer when a force is applied on it. For example, if the deformation is expressed as "dx", then when a force "F" is applied to a beam having a length "L", the deformation can be defined by the following equation (1):

(1)dx＝Kf*F*L³

wherein:

kf is the bending stiffness in (1/N mm)²)。

For example, for a length L of 100mm, the applied force F1N 0.1Kg and the bending stiffness Kf 10^-9The resulting deformation will be dx 10^-3mm。

In some embodiments, the thickness of the substrate 1100 may be between 1mm and 20mm, preferably between 2mm and 10mm, particularly when it is made of a material such as transparent acrylate (PMMA) or Polycarbonate (PC). It will be readily apparent to those skilled in the art, especially in view of the foregoing and following description, that the substrate thickness may vary due to the materials used for substrate 1100 and based on the properties of deformable light guide 1200.

Regarding the refractive index of the substrate 1100, there are mainly two configurations possible depending on the relationship of the refractive indices of the substrate 1100 and the deformable light guide 1200. That is, the refractive index of the substrate 1100 may be lower than the refractive index of the deformable light guide 1200 or higher than the refractive index of the deformable light guide 1200.

If the refractive index of the substrate 1100 is lower than the refractive index of the deformable light guide 1200, there is no requirement for transparency of the substrate 1100 since the sensing light does not substantially propagate therein. In this case, the substrate 1100 may be selected from any transparent material and color.

On the other hand, when the refractive index of the substrate 1100 is higher than that of the deformable light guide 1200, if the substrate 1100 is not substantially transparent or the attenuation loss thereof is excessively high, or the side of the substrate 1100 where the four edges support the deformable light guide 1200 is covered with a material having a high absorption coefficient for the wavelength of the sensing light, the sensing light is partially absorbed in the substrate 1100. This is particularly true for higher wave modes of light propagating in the deformable light guide 1200. This may result in a degraded signal-to-noise ratio at the receiver, resulting in an inability to detect light changes due to touch.

In this case, in some embodiments, our substrate 1100 is substantially transparent to the wavelength of the light sensed. By substantially transparent, it is meant that the substrate 1100 can have less than 30% loss in transmitted sensed light intensity, and ideally less than 10% loss in wavelength attenuation of transmitted sensed light. This would be particularly advantageous because it limits the energy loss propagating inside the light guide, avoids heat generation due to infrared radiation, thereby reducing power consumption and increasing the efficiency of smart surface 3000.

Alternatively, an additional layer (not shown) may be placed between the substrate 1100 and the deformable light guide 1200, which may cause total or substantially total internal reflection of the deformable light guide. In this case, the additional layer may be chosen to be of a lower index of refraction than the deformable light guide 1200.

We propose that the material chosen for the substrate 1100 comprises acrylic Plastic (PMMA) or Polycarbonate (PC), particularly when the wavelength of the sensing light is in the near infrared, i.e., from 0.7 μm to 2.5 μm, more desirably from 0.75 μm to 1.4 μm. Other thermoplastics, such as polypropylene (PP), Polyethylene (PE) and compounds thereof, glass (soda-lime-silica, borosilicate, phosphate) and glass-filled polymers may also be used. Glass-filled polymers refer to a range of moldable composite materials, with short glass fibers contained in the matrix of the polymer material.

Because near infrared light does not interfere with the visible spectrum, we particularly suggest the use. This allows the smart surface to operate without emitting visible light, which may be critical in certain applications, so that the smart surface 3000 can be used in dark environments and avoid any lighting effects. Furthermore, it allows the smart surface 3000 to be illuminated flexibly in a controlled manner according to requirements. That is, in those applications where the smart surface 3000 needs to be backlit, such as illuminating the 3000 surface and/or illuminating icons on the surface, the near-infrared sensing light does not interfere with the visible light used for backlighting to affect the operation of the smart surface 3000. Furthermore, this allows the smart surface to be used in the presence of external light that has little effect on the sensing operation of the smart surface 3000.

However, it will be clear that the invention is not limited to the use of near infrared as sensing light, for example light in the visible spectrum from 450 to 780nm may also be used as sensing light. The materials listed above may also operate in this visible spectrum, giving the sensing surface an afterglow of used visible colors.

The deformable light guide 1200 typically changes its light transmittance when deformed (e.g., when pressed). In particular, this may also occur due to geometrical changes in the shape of the deformable light guide 1200, which also has an effect on the transmission path of the sensing light. Additionally or alternatively, pressure exerted on the deformable light guide 1200 may locally change the physical properties of the deformable light guide 1200, thereby locally changing the transmissivity of the material.

In some implementations, the material of the deformable light guide can be considered to work under the assumption of a linear elastic regime. Based on this assumption, the modulus of elasticity of the material used for the deformable light guide 1200 may be adjusted and/or selected such that the maximum amount of deformation allowed over the maximum pressure is less than a predetermined value, e.g., 20% relative to the total thickness of the deformable light guide 1200, and certainly 10% better. In practical implementations, the maximum pressure of the smart surface 3000 may be in the range of 10MPa to 500 MPa. In this pressure range, it can be seen that the compression of the intermediate layer on the deformable light guide increases the loss by a factor of 4 to 5 compared to the loss value without any applied pressure.

In particular, in some embodiments, the material used for the deformable light guide 1200 uses the young's modulus method, which is three orders of magnitude smaller than the material used for the substrate 1100. In this case, most of the deformation due to the applied pressure results in compression of the deformable light guide 1200.

In some embodiments, the thickness of deformable light guide 1200 may be selected to be between 0.1mm and 5mm, preferably between 0.5mm and 2.5mm, without applying additional pressure.

In some implementations, it is desirable that the deformable light guide 1200 be transparent to the wavelengths of the light sensed.

In some implementations, the material of the deformable light guide 1200 can be selected without applying additional pressure thereto, such that the attenuation loss value of the sensing light is less than 10%, and more preferably less than 5%, over its total length. Once the length of the deformable light guide 1200 and the wavelength of the sensing light have been selected, it will be apparent to the skilled person how to achieve this by appropriate selection of materials and thicknesses.

A preferred material for the deformable light guide 1200 may be a material containing silicone rubber, especially when the wavelength of the sensing light is in the near infrared range. Other materials for the deformable light guide 1200 may include optically clear thermoplastic elastomers, which are typically block copolymers, such as styrene block copolymer compounds SEBS, SEPS, SBS, SIS, polyurethane elastomers (TPU), polyester elastomers (TPE), polyamide elastomers (TPA), and polypropylene compounds with rubber and/or polyolefin polymers. All of these thermoplastic elastomers can be substituted for silicone rubber. Transparent silicone rubbers have particularly advantageous properties for the transmission of light in the near infrared spectrum. They do not exhibit birefringence and do not exhibit a change in refractive index upon compression, which makes them suitable as materials for the deformable light guide 1200.

In some implementations, the deformable light guide 1200 may be attached to the support substrate 1100 by an adhesive or primer (preferably a primer or primer transparent to the sensing light) to ensure matching between the two mating surfaces and avoid light scattering phenomena due to surface optical discontinuities.

In some implementations, the ratio between the bending stiffness of the substrate 1100 and the deformable light guide 1200 (defined as the edge deformation ratio) can be chosen to be less than 0.2, and better still less than 0.1, along the vertical direction.

That is, in the elastic approximation state, both the substrate 1100 and the deformable light guide 1200 can be modeled as thin elastic plates, each having a thickness h_sAnd h_wThe staples are stapled together and all bend under the applied load. We further assume that in the absence of tangential forces at the interface of the substrate 1100 and the deformable light guide 1200, the edge deformation ratio can be considered an expression of the bending stiffness of the respective two layers. The edge deformation ratio can be expressed by the following equation (2)

(2) Edge deformation rate ═ E_s*h_s ³*(1-v_w ²)]/[E_w*h_w ³*(1-v_s ²)]

Wherein:

E_sis the young's modulus of the substrate 1100.

h_sIs the thickness of the substrate 1100;

v_sis the poisson's ratio of the substrate 1100;

E_wis the young's modulus of the deformable light guide 1200;

h_wis the thickness of the deformable light guide 1200;

v_wis the poisson's ratio of the deformable light guide 1200;

it may be noted that the edge deformation ratio may be ensured by appropriate choice of mechanical properties (e.g., elasticity) and design of the geometry (e.g., thickness between two layers) of the materials used for the substrate 1100 and the deformable light guide 1200.

The overlay 2500 is generally intended to provide a surface layer of the smart surface that a user may touch. That is, there will generally no further overlay layers on the overlay layer 2500, except for finish coatings, such as lacquers, varnishes or other coatings, which are used for aesthetic and/or scratch protection and/or tactile purposes. This is at least for the majority of the sensing surface of the overlay 2500, i.e. the touch detectable surface of the overlay 2500. The overlay 2500 may provide the smart surface 3000 with an aesthetically pleasing overlay that may be tactile.

Generally, the overlay 2500 is flexible enough to accommodate deformation caused by pressure exerted by a user on the smart surface 3000. In some implementations, this may be achieved by making the cover layer 2500 have a similar bending stiffness as the deformable light guide 1200.

Similar to the edge deformation ratio between the support 1100 and the deformable light guide 1200, the edge deformation ratio between the cover layer 2500 and the deformable light guide 1200 may also be calculated. In some embodiments, the value of the edge deformation ratio between the cover layer 2500 and the deformable light guide 1200 may be selected to be comprised between 2 and 0.5, preferably between 1.5 and 0.75, even more preferably between 1.2 and 0.8, even more preferably equal to 1.

The thickness of the cover layer 2500 is preferably 0.5mm to 2mm, more preferably 0.7 to 1.3mm, and even more preferably about 1 mm.

The cover layer 2500 may act as a protective cover for the deformable light guide 1200 and/or other components of the smart surface 3000. You can clearly see the function of the protective cover from the following description. The cover layer 2500 may have an aesthetic appearance and a pleasant tactile feel. The surface of the cover layer 2500 may be generally smooth on the side exposed to touch to reduce contact friction with a finger and to make the sliding operation of the finger easy and comfortable. However, this is not essential. In some embodiments, the overlay 2500 can have a small raised pattern or texture intended to guide the touch action of a user without affecting the flexibility of the overlay. The overlay 2500 may be optically opaque in visible light, translucent, transparent, frosted, or a mixture thereof.

The material for the overlay 2500 may include natural or synthetic leather, wood veneer, particle board, plastic pattern, velvet, fabric, metal, stainless steel, or stone. The above materials are examples and the present invention is not limited to these materials only.

The smart surface 3000 also includes an intermediate layer 3600 located between the deformable light guide 1200 and the cover layer 2500. The general purpose of the intermediate layer 3600 is to provide an interface between the deformable light guide 1200 and the inner surface 2520 that has known properties. This allows for various types of interior surfaces 2520 to be used, as the intermediate layer 3600 may at least partially compensate for those differences, allowing the deformable light guide 1200 to operate properly. This is particularly useful in situations where the characteristics of the inner surface 2520 cannot be precisely and uniformly controlled.

In some embodiments, the thickness of the intermediate layer may be in the range of 0.1mm to 3mm, better in the range of 0.3mm to 1mm, even more preferably about 0.5 mm.

In some implementations, the intermediate layer 3600 can be any material that meets at least one of the following criteria (C1-C3), or in some implementations, multiple or even all of the criteria:

(C1) the arithmetic average roughness is more than twice the wavelength used to sense light.

This advantageously avoids diffraction effects like diffraction gratings, changing the sensing principle from an optical attenuation loss based model to a scattering loss model, thereby not complicating or distorting the pressure information retrieval. By using a material with an arithmetic mean roughness greater than the upper threshold, the post-processing of the signal received by the receiver of the sensed light can be simplified, since we can assume that the direction of the sensed light does not change due to the loss of light energy caused by the presence of pressure on the surface.

In particular, under the simplified assumption of the single slit diffraction model, we can analyze the effect of the roughness of the intermediate layer 3600 on the deformable light guide 1200. Under such conditions, the arithmetic mean roughness R_aAnd the relationship between the wavelength λ for sensing light is given by the following equation (3)

(3)R_a*Sin(theta_min)＝λ

Wherein:

R_ais the arithmetic mean roughness of the wafer,

λ is the wavelength for sensing light, and

theta_minis the diffraction angle.

Diffraction phenomena are associated with high diffraction angles. Thus, in some embodiments, the diffraction angle is kept at a low level, so that the effect of diffraction is small. The inventors have found that when R is_a2 x λ, diffraction angle theta_minAt 30 degrees, the general implementation is very good, it avoids the effects of diffraction, and R is_aThe value of (d) is higher.

(C2) The intermediate layer 3600 at least partially absorbs wavelengths of sensing light, which we desire to have an attenuation loss at least twice that of the deformable light guide 1200.

In some embodiments, attenuation loss refers to the loss measured when the intermediate layer 3600 is pressed against the deformable light guide 1200 at a uniform pressure of 0.3psi to 0.7psi, more preferably 0.5psi, across the smart surface 3000. These values were chosen because they represent the average force a person would hit on the keyboard, as determined experimentally by the inventors.

This feature (intermediate layer 3600 at least partially absorbing the wavelength of the sensing light) further contributes to increasing the attenuation loss of the sensing light when pressure is present on smart surface 3000. Whenever the intermediate layer 3600 is pressed against the deformable light guide 1200, the sensing light transmitted in the deformable light guide 1200 is attenuated due to the deformation of the finger pressing surface, rather than being internally reflected.

(C3) If voids in the intermediate layer 3600 are present, they may be filled with a substance, preferably air, such that the refractive index value of the substance in the voids divided by the refractive index of the deformable light guide 1200 material is less than 1, more preferably less than 0.8, and most preferably less than 0.75.

The ratio between the index of refraction of the substance in the void and the material of the deformable light guide 1200 determines the total internal reflection angle of the deformable light guide 1200. In the resting state, no pressure is applied to the smart surface 3000, by selecting a ratio less than 1, to have a large total internal reflection angle, thus allowing all light rays having an angle less than total internal reflection to be reflected and transmitted to the end of the deformable light guide 1200.

Fig. 4A schematically shows a top view of a possible implementation of the intermediate layer 3600. In this implementation, the middle layer 3600 is a wire mesh 4400, the wire mesh 4400 being a matrix separated by horizontal and

vertical wires

4420 and 4410, with gaps between the horizontal and/or vertical wires. The diameter of the wires (horizontal, vertical) of the wire mesh is typically between 0.1mm and 1.2 mm. Whereas the thickness of the wire mesh is generally equal to the diameter of the wire used (horizontal, vertical). The spacing between the wires determines the void area. The area of the voids 4440 is typically less than 10 times the square of the diameter of the wire used. In other embodiments, the wire mesh may use more than two wire directions, and the spacing of the wires may be in a regular pattern, such as a fabric, or an irregular pattern, such as a woven fiber weave.

Fig. 4B and 4C schematically show a top view and a weft cut section of a possible embodiment of the intermediate layer 3600. In this embodiment, the intermediate layer 3600 is realized by a fabric 4600, which is a fabric made by interweaving two or more threads: the warp 4610, weft 4620 are angled 4630 with respect to each other.

Preferred materials for the warp 4610 and weft 4620 include synthetic and/or natural fibers, polyester, acrylate, cotton and mixtures of these materials. In some embodiments, it is desirable to select a material that does not swell due to humidity, as this can cause bumps in the smart surface 3000 and affect sensor performance. For example, materials having a hydration expansion coefficient of less than 50%, preferably less than 30%, can be selected.

In some implementations, the material is selected to not adhere to the surface of the deformable light guide 1200, allowing 3600 to be able to recover mechanically from compression quickly without the appearance of a slow creep recovery condition. Once the material for deformable light guide 1200 has been selected, it will be apparent to one skilled in the art how to select suitable materials for warp 4646 and weft 4620 to reduce their adhesion to deformable light guide 1200.

Fig. 4D schematically shows an enlarged portion S3 of fig. 4C. Given the size of the warp 4610 and weft 4620, the arithmetic mean roughness may be obtained by geometric considerations. As shown in fig. 4D, the following dimensions may be defined:

d 1: diameter of warp 4610;

d 2: the diameter of weft 4620;

p 1: distance between adjacent warp threads 4610;

p 2: the distance between adjacent weft yarns 4620, not shown, may be measured by the method of measuring p1 in a warp yarn section;

α 1: the angle of the weft 4620 relative to horizontal;

α 2: the angle of the warp 4610, not shown, can be measured by measuring α 1 in a cross section of the warp;

l1: the length of the weft 4620 between the centers of two consecutive warp 4610;

l2: the length of the warp 4610 between the centers of two consecutive weft 4620 is not shown, but may be measured by the method of measuring L1 in the warp section.

In some embodiments, the angles α 1 and α 2 are measured at linear portions of the respective warp and weft. Alternatively, or in addition, the angle α 1 is measured at the position of the weft thread 4620 in the middle of two consecutive warp threads 4610 and/or the angle α 2 is measured at the position of the warp thread 4610 in the middle of two consecutive weft threads 4620. Further alternatively or additionally, the angles α 1 and α 2 may be defined as the maximum angle of the respective warp and weft with respect to the horizontal direction.

Further, in some embodiments, the horizontal direction may be defined as a direction that linearly interpolates the centers of two or more consecutive warp threads 4610, or a direction that is linearly interpolated the centers of two or more consecutive weft threads 4620, or a direction of maximum extension of the fabric.

When near infrared light is used as the sensing light, the preferred values are:

d1 and/or d2 of between 0.1 and 1.2mm, preferably between 0.5 and 1mm, and/or

α 1 and α 2 are greater than 6 degrees, preferably greater than 30 degrees, and/or

-p1 and/or p2 is greater than [ (d1+ d2)/2+2 x λ ], wherein λ is the wavelength of the sensing light. In practical embodiments, p1 and p2 typically range from 0.5mm to 3 mm.

The arithmetic mean roughness Ra can then be generally or at least approximately calculated by the following equation (4):

(4)Ra＝1/4*[(L1-D*α1)*sin(α1)+(L2-D*α2)*sin(α2)+D*(2-cos(α1)-cos(α2)]

wherein

-Ra is the average arithmetic roughness;

-D＝d1+d2；

α 1 and α 2 are the angles of the warp 4610 and weft 4620 in the weft and warp directions, respectively, and

l1 and L2 are the length of the weft and warp axes between the centers of successive threads.

Although the warp 4610 and weft 4620 have been schematically illustrated as having a circular cross-section, it will be clear that the invention is not so limited. Other cross-sectional shapes may alternatively be implemented, such as oval, arcuate, lenticular, square, rectangular, and the like.

As shown, in most commercially available woven materials, the angle between the weft and warp threads, i.e., angle 4630 shown in fig. 4B, is conventionally about 90 degrees. However, it will be clear that the invention is not so limited, and can be applied from 0 to 180 degrees.

Although first fabric 4600 has been shown to include only a single layer, in some embodiments, a plurality of such layers may be stacked on top of each other to implement first fabric 4600.

Overall, the use of a single interlayer 3600 makes the smart surface thinner and exhibits greater flexibility. A single layer is generally sufficient when the voids in first fabric 4600 are filled with a compressible material (e.g., air). Conversely, when the voids are filled with an incompressible material such as oil, silicone oil, glycerin, propylene glycol or ethylene glycol, as well as other oils having a viscosity between 1 and 2000mPa sec, or any combination thereof, it is recommended to select more interlayers, such as two interlayers 3600, in some embodiments three or more interlayers 3600, because this will advantageously reduce the flow resistance of the filling material when compressed. More intermediate layers 3600 increase porosity compared to a single intermediate layer 3600. When displaced due to deformation caused by pressing the finger, the flow of the filling material in the surrounding area is made easier.

Fig. 5 schematically shows a top view of a second fabric 5600, which may be used as an alternative to implementing the middle layer 3600. The second fabric 5600 differs from the first fabric 4600 due to the presence of different threads. That is, although the warp 4610 and the weft 4620 are substantially the same in the second woven fabric, the first, second, third and

fourth threads

5610, 5611, 5620, 5621 of the second woven fabric 5600 may be different. In particular, the lines may include a first type of line (first line 5610, second line 5611) in a first direction and a second type of line (third line 5620, fourth line 5621) in a second direction.

In one implementation, the first type of line may include a first line 5610 and a second line 5611, the physical characteristics of the first line 5610 being different from the physical characteristics of the second line 5611.

This is particularly advantageous for the selective adhesion of the intermediate layer 3600 to the surface of the deformable light guide 1200. Either of the first and

second lines

5610 and 5611 may be adhered to the deformable light guide 1200, and for ease of discussion, taking the second line 5611 as an example, we consider the second line 5611 to be more easily adhered to the deformable light guide 1200 than the first line 5610, hereinafter. To accomplish this, the second wire 5611 may be impregnated with an adhesive chemical and/or primer for this purpose, and in some cases may be activated by heating and/or increasing humidity. This allows the second lines 5611 to adhere to the deformable light guide 1200 more than the first lines 5610 and allows the intermediate layer 3600 to anchor to the deformable light guide 1200. Examples of the bonding chemicals and/or primers may include silicone glues using any silane based primers and reactants. The threads may be impregnated prior to forming the fabric, so that only some of the threads may be impregnated if desired. Alternatively or additionally, another method for selectively saturating only a portion of the threads is to change the wettability of the threads to make them more hydrophilic or hydrophobic so that after the fabric is formed, the fabric can be wetted with a primer, which may be just dipped into the set threads.

Alternatively or additionally, the second line 5611 may be implemented with a different material than the first line 5610, in particular by selecting a material for the second line 5611 that has a higher adhesion to the material of the deformable light guide 1200 than the material of the first line 5610.

In some embodiments, the presence of the different types of first and

second strands

5610, 5611 may stiffen the intermediate layer 3600, thereby better reducing the effects of tensile and/or shear stresses applied by user interaction and/or lateral securing devices of the intermediate layer 3600. This can be achieved, for example, by: some of the wires, such as second wire 5611, are of a stiffer material than other wires, such as first wire 5610. In some embodiments, the more rigid second wire 5611 may preferably be 10 times as rigid as the less rigid first wire 5610. Alternatively, or in addition, the cross-section of the more rigid wire is increased to 4 times the less rigid wire, preferably 2 times. This range is particularly advantageous as it allows differences in stiffness to be achieved without significantly affecting the spatial uniformity of the sensing.

In some embodiments, the ratio of the second line 5611 to the total number of the first and

second lines

5610 and 5611 is preferably between 1% and 20%, and more preferably between 2% and 10%. We have found that this advantageously increases adhesion and/or increases stiffness without affecting the sensing operation.

In some implementation cases, the second type of lines may include a third line 5620 and a fourth line 5621, wherein the physical characteristics of the third line 5620 are different from the physical characteristics of the fourth line 5621.

In yet another implementation, such as the implementation shown in fig. 5, the two solutions may be implemented together such that the first type of line may include a first line 5610 and a second line 5611, wherein the physical characteristics of the first line 5610 are different from the physical characteristics of the second line 5611, and the second type of line may include a third line 5620 and a fourth line 5621, wherein the physical characteristics of the third line 5620 are different from the fourth line 5621.

The same considerations as for the first and

second lines

5610 and 5611 apply to the third and

fourth lines

5620 and 5621. It is obvious that we can realize various possible combinations of different characteristics. For example, the second line 5611 may be provided with increased adhesion to the deformable light guide 1200, while the fourth line 5621 may be provided with increased stiffness. As another example, we can provide increased adhesion and stiffness to the second wire 5611, while we can provide only increased stiffness to the fourth wire 5621

The present invention describes several referenced embodiments. Each of these embodiments has been described as including one or more features. It is to be understood that other embodiments may be practiced by combining one or more features from one or more embodiments that are within the purview of this patent. Moreover, it should be clear that implementing one feature of these embodiments does not necessarily require implementing all other features from that embodiment.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A smart surface for detecting the location and/or pressure of at least one touch, the smart surface comprising: a support substrate (1100), a deformable light guide (1200), and a cover layer (2500); the deformable light guide (1200) is located above a support substrate (1100), sensing light being transmittable through the deformable light guide (1200);

a cover layer (2500) over the deformable light guide (1200) the cover layer (2500); characterized in that it further comprises an intermediate layer (3600) located between the deformable light guide (1200) and the cover layer (2500).

2. A smart surface according to claim 1,

the intermediate layer (3600) has an arithmetic average roughness greater than twice the wavelength of the sensing light.

3. Intelligent surface according to claim 1 or 2,

the intermediate layer (3600) at least partially absorbs wavelengths of the sensing light.

4. A smart surface according to any one of claims 1-3,

the attenuation loss of the intermediate layer (3600) is at least twice the attenuation loss of the deformable light guide (1200).

5. A smart surface according to any one of claims 1-4,

the intermediate layer (3600) comprises voids filled with a substance having a refractive index divided by a refractive index of a material of the deformable light guide (1200) of less than 1; preferably, the value of the refractive index of the substance divided by the refractive index of the material of the deformable light guide (1200) is less than 0.8; more preferably, the value of the refractive index of the substance divided by the refractive index of the material of the deformable light guide (1200) is less than 0.75.

6. A smart surface according to any one of claims 1-5,

the intermediate layer (3600) comprises a wire mesh (4400).

7. A smart surface according to claim 6,

the wire mesh (4400) comprises vertical wires (4410), horizontal wires (4420) and gaps (4440); the diameters of the vertical lines (4410) and the horizontal lines (4420) range from 0.1 to 1.2mm, and the area of the gap (4440) is less than 10 times the square of the diameter of the vertical lines (4410) or the horizontal lines (4420).

8. A smart surface according to claim 5,

the intermediate layer (3600) comprises a fabric.

9. The smart surface of claim 8,

the fabric comprises warp (4610) and weft (4620);

the warp (4610) has a first diameter, the first diameter ranging in size between 0.1mm and 1.2 mm; preferably, the first diameter ranges in size between 0.5mm and 1 mm; and/or the presence of a gas in the gas,

the weft (4620) has a second diameter, the size of the second diameter ranging between 0.1mm and 1.2 mm; preferably, the second diameter ranges in size from 0.5mm to 1 mm.

10. The smart surface of claim 8,

the fabric comprises warp (4610) and weft (4620);

the first angle of the weft (4620) with respect to the horizontal is greater than 6 degrees, preferably greater than 30 degrees or more; and/or the presence of a gas in the gas,

the second angle of the warp (4610) with respect to the horizontal is greater than 6 degrees, preferably greater than 30 degrees.

11. The smart surface of claim 8,

the fabric comprises warp (4610) and weft (4620);

adjacent said warp threads (4610) have a first distance of between 0.5mm and 3mm and/or adjacent said weft threads (4620) have a second distance of between 0.5mm and 3 mm.

12. The smart surface of claim 8,

the fabric comprises warp (4610) and weft (4620);

the warp threads (4610) have a first diameter and the weft threads (4620) have a second diameter;

the warp threads (4610) have a first distance and the weft threads (4620) have a second distance;

the first distance (p1) and/or the second distance (p2) is greater than [ (d1+ d2)/2+2 x λ ];

where p1 is a first distance, p2 is a second distance, d1 is a first diameter, d2 is a second diameter, and λ is the wavelength of the sensing light.