Improved devices using haptic technologies

Abstract

The present invention relates to improved devices with a coating layer, using haptic technologies, specifically designed to provide tactile feedback and interactive experience to users. More specifically, the invention relates to haptic systems and methods applicable across various industries, including but not limited to consumer electronics, virtual reality (VR), augmented reality (AR), gaming, healthcare, robotics, museums, medical application and automotive applications. The invention also relates to a tactile / vibrational human-machine interface system that can be used in conjunction with many devices and objects in daily life, taking their effectiveness to the next level.

Description

[0001] Improved Devices Using Haptic Technologies

[0002] The present invention relates to improved devices with a coating layer, using haptic technologies, specifically designed to provide tactile feedback and interactive experience to users. More specifically, the invention relates to haptic systems and methods applicable across various industries, including but not limited to consumer electronics, virtual reality (VR), augmented reality (AR), gaming, healthcare, robotics, museums, medical application and automotive applications. The invention also relates to a tactile / vibrational human-machine interface system that can be used in conjunction with many devices and objects in daily life, taking their effectiveness to the next level.

[0003] The term haptik was first used by the German Psychologist Max Dessoir in 1892, when suggesting a name for academic research into the sense of touch in the style of that in "acoustics" and "optics".

[0004] Gibson (1966) defined the haptic system as "The sensibility of the individual to the world adjacent to his body by use of his body". Gibson and others further emphasized what Weber had realized in 1851 : the close interdependence of haptic perception and body movement, and that haptic perception is active exploration.

[0005] The concept of haptic perception is related to the concept of extended physiological proprioception, according to which when a tool such as a stick is used, perceptual experience is transparently transferred to the end of the tool. Haptic perception relies on the forces experienced during touch. This allows the creation of "virtual", illusory haptic shapes with different perceived qualities, which has clear application in haptic technology.

[0006] The electrical attraction between a charged surface and human skin was discovered by Johnsen and Rahbek in 1923. Later, in 1953, Mallinckrodt reported an increase in the friction during touch when an alternating voltage is applied to an insulated aluminum plate. This effect is now intensively studied in the context of touchscreen applications where one is interested in modulating the friction between the human finger and the touchscreen to display haptic feedback to the user for augmented or alternative sensorial experience. Hence, understanding the physics behind this bioelectromechanical interaction and studying the material science for the surface chemistry of the touchscreen can provide the step forward into the development of this technology not only for online shopping, education, gaming, and data visualization but also for rehabilitative medicine and user interface development for blind people.

[0007] Haptic feedback refers to the sense of touch or tactile sensations that are artificially generated and conveyed to users through electronic devices or systems. Haptic technologies have evolved significantly in recent years, enabling the creation of more immersive and interactive user experiences. Traditional user interfaces primarily rely on visual and auditory feedback, which may not always provide the desired level of engagement, realism, or accessibility.

[0008] Haptic feedback mechanisms have gained prominence due to their ability to complement or enhance visual and auditory interfaces, providing users with a more holistic and intuitive means of interaction. Haptic technologies encompass a range of techniques, including but not limited to vibration, force feedback, texture rendering, temperature variation, and pressure simulation, among others.

[0009] Haptic feedback is commonly used in arcade games, especially racing video games. In 1976, Sega's motorbike game Moto-Cross, also known as Fonz, was among the first games to use haptic feedback, causing the handlebars to vibrate during a collision with another vehicle. Tatsumi's TX-1 introduced force feedback to car driving games in 1983. The game Earthshaker! added haptic feedback to a pinball machine in 1989.

[0010] US3780225A which is a US patent for a tactile telephone was granted to Thomas D. Shannon in 1973. An early tactile man-machine communication system was constructed by A. Michael Noll at Bell Telephone Laboratories, Inc. in the early 1970s and US3919691 A patent was issued for his invention in 1975.

[0011] In 1994 the Aura Interactor vest, was developed. The vest is a wearable force-feedback device that monitors an audio signal and uses electromagnetic actuator technology to convert bass sound waves into vibrations that can represent such actions as a punch or kick. The vest plugs into the audio output of a stereo, TV, or VCR and the audio signal is reproduced through a speaker embedded in the vest.

[0012] In 1995, Thomas Massie developed US5587937A the Phantom (Personal Haptic Interface Mechanism) system. It used thimble-like receptacles at the end of computerized arms into which a person's fingers could be inserted, allowing them to "feel" an object on a computer screen.

[0013] In 1995, Norwegian Geir Jensen described a wristwatch haptic device with a skin tap mechanism, termed Tap-in. The wristwatch would connect to a mobile phone via Bluetooth, and tapping-frequency patterns would enable the wearer to respond to callers with selected short messages.

[0014] In 2015, the Apple Watch was launched. It uses skin tap sensing to deliver notifications and alerts from the mobile phone of the watch wearer.

[0015] With the prevalence of smartphones in the last decade, touch screens are everywhere in our daily life: mobile phones, kiosks, notebooks, tablet PCs, control interfaces of smart home appliances, etc. However, they mostly lack haptic feedback on their surface, which, as a supportive sensory channel, could have a high potential to improve task performance and usability.

[0016] Haptic feedback, despite its numerous advantages, is not as widespread as it should have been but it is already utilized in various applications. Nevertheless, there remains a need for further advancements in terms of precision, realism, energy efficiency, and adaptability to different applications. This may be the reason for its lag in developing or advancing in different applications. Generating localized haptic feedback on touch displays has also been a challenge in recent years. For instance, in the field of consumer electronics, there is a growing demand for more immersive haptic feedback in smartphones, wearables, and virtual reality devices. In healthcare, haptic technologies can play a crucial role in surgical simulators, telemedicine, and rehabilitation devices. In the automotive industry, haptic feedback can enhance user interfaces, driver assistance systems, and safety features, providing drivers with intuitive and informative tactile cues. Haptic technologies have undergone significant development in the past, reaching to a point where progress has slowed down preventing to meet the necessities required for bringing the haptic technology to greater populations. To advance further, attention must be directed towards enhancing surface chemistry. With this object, delving into the molecular intricacies of surface interactions, it has been possible to reignite innovation in haptic technologies, unlocking new possibilities of tactile feedback and sensory immersion. The studies in the scope of the present invention on surface chemistry provided novel functionalities in haptic experiences.

[0017] Haptic technologies are employed in various devices across different industries to provide users with tactile feedback, enhancing their interaction and engagement. Several examples without being limited to these are smartphones, tablets, gaming consoles, controllers, wearable devices such as smartwatches and fitness trackers, virtual reality and augmented reality headsets, automotive interfaces where drivers can interact with touchscreen interfaces more safely and intuitively without needing to divert their attention from the road, medical devices with various applications including surgical simulation, training and rehabilitation and industrial and manufacturing equipment.

[0018] These examples show the diverse range of devices that utilize haptic technologies across different industries.

[0019] Among these devices, smartphones are an important aspect for the daily life of many people in the modern days. Considering the other types of devices having a touchscreen it is entirely possible to provide improvements that could be applied to all of these with a direct impact to millions of people. Nowadays, capacitive touch screens have become one of the most essential parts of smartphones, tablets, and notebooks. These screens detect the finger position and help the user interact with text, pictures, and other digital information. One important effort to make this interaction more effective is to display tactile feedback to the user through the use of electrostatic forces to increase the physicality of touch interaction and / or to improve haptic perception. When an alternating electric potential is applied to the conductive layer of a surface capacitive touchscreen, the insulating layer on the glass plate and the finger are polarized by induction. Thus, an electrostatic attraction force is generated between the finger and the counter surface, which increases the sliding friction between them. This phenomenon was referred to as “electrovibration” by Grimnes, who also reported that the perceived tactile sensation depends on the roughness and moisture of the finger. Thus, haptic technologies heavily rely on the finger of a user and its interaction with the surface of a touchscreen. As a consequence, the improvements relating to haptic technologies must focus on the surface chemistry of touchscreens.

[0020] Over the last decades, two main methods to obtain haptic feedback on touch screens have stood out: (1 ) electrostatic actuation and (2) electromechanical actuation. In the former method, a conductive transparent layer (i.e., indium tin oxide (ITO) films) embedded in the touch screen is excited with alternating voltages. The latter is performed using different types of electromechanical actuators such as vibration motors, linear actuators, piezoelectric patches, and electroactive polymers, which are mechanically coupled to the touch screen. In the former method, a conductive transparent layer (i.e., indium tin oxide (ITO) films) embedded in the touch screen is excited with alternating voltages.

[0021] In a capacitive touch screen, the screen includes a transparent conductive material, typically indium tin oxide (ITO). This conductive layer forms an array of electrodes that are arranged in rows and columns across the surface of the display. Electrostatic actuation requires the relative movement of the user’s finger on the display at all times because it is mainly based on the change in friction force between the display surface and the finger. When a user touches the screen with their finger or a conductive object, it creates a change in capacitance at the point of contact. This change in capacitance is detected by the electrodes in the display. The touch screen is connected to a controller, which processes the signals from the electrodes and determines the position and characteristics of the touch input. The controller then sends this information to the device's operating system, which translates it into appropriate actions or gestures. The electrostatic force, and hence the friction force, can be easily manipulated by varying the excitation voltage with a microcontroller. Moreover, touch interface systems that are actuated electrostatically do not include mechanically moving parts, which would reduce the lifespan of the appliance. The surface capacitive touch sensor (Model: 3M SCT3250) may be used to implement the electrostatic actuation method. Here, the amplified excitation voltage is applied to the electrode embedded in the touch display, and the electric charges are evenly distributed on the entire conductive layer. Therefore, during a particular time period, only one haptic effect can be sensed by the contacting finger on a surface capacitive sensor. We refer to the finger of the current / different user by saying “natural stylus”. It is actually a tactile illusion that the user gets different feedback at different locations of the electrostatically actuated single-touch display. A second natural stylus would perceive the same haptic feedback, even if it contacted a different location simultaneously. At this point, one of the biggest drawbacks arises: there is actually no multi-haptic feedback in prior art applications when the widely used devices are considered.

[0022] The common component in electromechanics actuation utilizing haptic technologies is a haptic actuator. An actuator is a component of a machine that produces force, torque, or displacement, usually in a controlled way, when an electrical, pneumatic or hydraulic input is supplied to it in a system (called an actuating system). An actuator converts such an input signal into the required form of mechanical energy. It is a type of transducer. In simple terms, it is a "mover". It requires a control device (controlled by control signal) and a source of energy. The control signal has relatively low energy and may be electric voltage or current, pneumatic, or hydraulic fluid pressure, or even human power. In the electric, hydraulic, and pneumatic sense, it is a form of automation or automatic control. The displacement achieved is commonly linear or rotational, as exemplified by linear motors and rotary motors, respectively. Rotary motion is more natural for small machines making large displacements. By means of a leadscrew, rotary motion can be adapted to function as a linear actuator (a linear motion, but not a linear motor). Another broad classification of actuators separates them into two types: incremental-drive actuators and continuous-drive actuators. Stepper motors are one type of incremental-drive actuators. Examples of continuous-drive actuators include DC torque motors, induction motors, hydraulic and pneumatic motors, and piston-cylinder drives (rams).

[0023] Commonly known haptic actuators include the types of eccentric rotating mass (ERM) motors, linear resonant actuators (LRAs), thermoelectric device, solenoid actuator, sltrasonic transducer or sensor and piezo haptic actuators. In addition to these, advanced soft materials have displayed promising performances in terms of haptic actuator development. A similar haptic localization issue applies to the second method (electromechanical actuation), since the actuators vibrate the entire surface to which they are attached. Moreover, in this method it is necessary to mount the actuators not beneath the display area, but rather under the peripheral edges (i.e. , screen bezels or the surface borders, excluding the visual area), since they would obviously block the visual information coming from the display. So, focusing the produced vibration on the desired locations is a new research problem. Nevertheless, there are some signal-processing solutions that can overcome the problem of haptic feedback localization. This technique is called time-reversal focusing, where the mechanical waves generated by multiple piezoelectric actuators are spatially and temporally focused. However, they are not easy to implement and might require considerable processing power.

[0024] Ege and Balikci, in their article titled “Transparent Localized Haptics: Utilization of PVDF Actuators on Touch Displays”, proposed a simple but effective method to generate accurate localized haptic feedback on displays using soft materials. They mounted transparent polyvinylidene fluoride (PVDF) actuators beneath the touch surface and characterized operating parameters according to human factors.

[0025] Utilizing haptic actuators has aroused a lot of interest in a variety of highly valued applications, especially in educating doctors on complicated surgeries or engineers on running expensive machinery.

[0026] Surface chemistry plays a crucial role in the design and functionality of tactile surfaces, which are surfaces that are specifically engineered to provide tactile feedback or sensations to users. Some key aspects of surface chemistry relevant to tactile surfaces in the context of the present invention are explained hereinbelow:

[0027] Surface chemistry influences the selection of materials for tactile surfaces. Materials with specific surface properties such as roughness, softness, or texture are often chosen to enhance tactile sensations. According to the present invention, elastomers or polymers with tailored surface functionalities may be selected to provide desired tactile feedback. Surface chemistry also affects the texture and roughness of tactile surfaces, which in turn influence the perception of tactile sensations. Chemical modifications or coatings can be applied to alter surface roughness and texture, enhancing or dampening tactile feedback as desired.

[0028] Additionally, surface chemistry impacts adhesion and friction properties, which are important for tactile surfaces intended for gripping or haptic feedback. Modifying surface chemistry through treatments or coatings can adjust adhesion and friction to optimize tactile performance. Surface wettability and energy influence interactions with liquids and other materials in contact with the tactile surface. Controlling surface chemistry can alter wettability, affecting how fluids spread or repel on the surface, which may be relevant for applications such as touchscreens or medical devices.

[0029] Chemical sensing and detection is also in the scope of present invention. Tactile surfaces may incorporate chemical sensing capabilities for applications such as detecting contaminants or analyzing surface properties. Surface chemistry plays a crucial role in designing surfaces with specific chemical reactivity or selectivity for targeted sensing applications.

[0030] Surface chemistry influences also the durability and stability of tactile surfaces under various environmental conditions, such as exposure to moisture, temperature fluctuations, or mechanical stress. Surface treatments or coatings can enhance durability by providing protective layers or modifying surface properties to resist degradation.

[0031] For tactile surfaces intended for applications involving continuous human contact or interaction, such as in prosthetics or wearable devices, surface chemistry is also important for ensuring biocompatibility and safety. Materials and surface treatments must be selected to minimize adverse reactions or irritation upon contact with the skin.

[0032] It is also possible that surface chemistry can be engineered to impart self-cleaning or anti-fouling properties to tactile surfaces, reducing the buildup of contaminants or debris that may affect tactile performance or hygiene in applications such as touch interfaces or consumer electronics.

[0033] Overall, understanding and controlling surface chemistry is essential for designing tactile surfaces with tailored properties to meet specific performance requirements and enhance user experiences.

[0034] Currently, there are no products that provide virtual tactile sensations through smart devices and surfaces in an ideal way or even if there are products the results are not satisfactory and users encounter the difficulty of this in many areas. Therefore, the present invention, which provides a technology that will make a difference in many fields such as education, advertising, entertainment, gaming, clothing, virtual stores, marketing, interior and exterior architecture, and user interfaces, has a wide range of applications. In the education sector, haptic human-machine interface systems, when applied to smart displays, help students at all levels, but especially in preschool and primary school, to learn basic scientific concepts more easily by directly experiencing them. For example, in preschool or primary school, students can feel the skins of different types of animals by sliding their fingers over the images of these animals. Similarly, in a science lesson, when a student wants to learn about frictional force between objects, they will feel a resistance force when they try to move the image of the object on the screen with their finger. As the object becomes heavier, the frictional force increases, so the resistance force the student feels also increases, thus gaining an understanding of frictional force. Another example is when a student who only hears that particles with the same electric charge repel each other and tries to understand it through a diagram, they will feel a resistance force when they move these particles closer to each other on the tangible touchscreen.

[0035] In the clothing sector, with interaction-based haptic system of the present invention integrated into store windows, customers will be able to feel the texture of textile products and gain insights about the products through the display placed on the storefront, without even entering the store. Considering the natural curiosity in humans to try new things, this system has tremendous advertising potential for clothing companies. Similarly, in the entertainment industry, games can be enriched by adding haptic effects to visual and auditory effects, attracting the interest of more users. In short, the haptic system of the present invention takes virtual reality one step further by allowing users to touch computer, tablet, or phone screens and feel the objects and interactions on the screen. Interfaces used in everyday life such as televisions, mobile phones, computers, and tablets, which enable our interaction with the virtual world, have only provided us with visual and auditory data since their invention until today. However, considering daily life, it is evident that the sense of touch assists us in many areas: the properties of surfaces such as roughness, smoothness, sharpness, and flexibility, as well as the vibrations and temperatures of objects, are perceived through the human's largest sensory organ, the skin. Therefore, it is apparent that the lack of the sense of touch in human interaction with the external world can lead to certain problems. For example, one of the biggest issues with touch-screen phones is that they cannot be easily used without looking at their screens. The reason for this is the inability to feel the act of pressing a virtual button on the touch screen, and the necessity to guide the fingers solely using visual cues. This restricts human interaction with the virtual world, confining communication to only the visual and auditory channels.

[0036] In the context of haptic technologies and the electrode region, semiconducting materials are commonly used in the construction of various electronic components, including transistors, sensors, and integrated circuits. The specific type of semiconducting material used in the electrode region depends on the application and the requirements of the device. Here are some commonly used semiconducting materials:

[0037] Silicon (Si): Silicon is the most widely used semiconductor material in electronics. It is a fundamental component of many integrated circuits, including those used in haptic devices. Silicon-based transistors and sensors are common in electronic components.

[0038] Gallium Arsenide (GaAs): GaAs is another semiconductor material that is used in certain electronic devices. It has advantages in high-frequency applications and is sometimes chosen for specific components in haptic technologies.

[0039] Indium Phosphide (InP): InP is a semiconductor material used in applications requiring high-speed electronic components. It is used in certain specialized devices where its properties are advantageous.

[0040] Organic Semiconductors: Some haptic devices and flexible electronics use organic semiconductors, which are carbon-based materials. Organic semiconductors can be more flexible than traditional inorganic semiconductors, allowing for the creation of flexible and stretchable electronic components.

[0041] Polymer Semiconductors: Conductive polymers, such as polythiophene and polyaniline, can also be used in the electrode region of haptic devices. These materials offer flexibility and are suitable for certain types of applications.

[0042] Amorphous Silicon (a-Si): Amorphous silicon is a non-crystalline form of silicon and is used in thin-film transistors (TFTs). It can be employed in the construction of certain display and touch-sensitive elements in haptic devices.

[0043] The specific choice of semiconductor material depends on factors such as the device's performance requirements, cost considerations, and the desired properties of the electrodes in the haptic technology.

[0044] The haptic technology described in this invention offers versatility and scalability, making it applicable across a wide range of industries. Its modular architecture and compatibility with existing devices and systems facilitate easy integration into new and established products.

[0045] Furthermore, the present invention incorporates energy-efficient designs, optimizing power consumption without compromising the quality of haptic experiences. This enables prolonged battery life in portable devices and reduces overall energy consumption in various applications.

[0046] The embodiments and methods described herein provide substantial advancements in the field of haptic technologies, allowing for more immersive, realistic, and interactive user experiences.

[0047] The idea of the haptic screen is based on the concept of fully touching and feeling objects on the screen; it can be applied to any screen and in all areas where tactile interaction is present. It has numerous applications, including education, advertising, textiles, entertainment, and online shopping in stores and on the internet. Although there are several prior art documents addressing the similar problems, none of these effectively solve the problems that exist in the prior art in an ideal way.

[0048] The present invention addresses the aforementioned challenges and provides an improved haptic technology that offers enhanced precision, realism, energy efficiency, and adaptability. The invention encompasses novel hardware components, sophisticated algorithms, and innovative methods for generating and delivering haptic feedback.

[0049] By leveraging advancements in sensor technology, actuators, materials, and signal processing techniques, the invention achieves higher levels of haptic fidelity and responsiveness. The system intelligently detects and interprets user input, environmental conditions, and application-specific requirements, allowing for tailored and context-aware haptic feedback.

[0050] The touchscreen of the improved haptic devices according to the present invention comprises, a substrate as the base layer, a transparent conductive layer, a dielectric layer beneath the transparent conductive layer, touch sensing elements within or beneath the transparent conductive layer and dielectric layer and a coating layer incorporated on the transparent conductive layer.

[0051] The substrate layer of the touchscreen is produced from glass or plastic materials wherein the glass can be selected from the list comprising soda lime glass, aluminosilicate glass and gorilla glass. In some embodiments of the present invention plastic or polymeric materials are used selected from the list comprising, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyimide, polyethylene naphthalate. In other embodiments composite materials such as glass polymer composites or ceramics such as aluminum oxide is used.

[0052] The transparent conductive layer is produced from indium tin oxide. This is the outer layer of the touchscreen responsible for detecting touch inputs. The coating layer deposited over the transparent conductive layer is an important aspect of the present invention. The composition of the coating may be tailored in order to provide anti glare or anti finger print characteristics to the touchscreen. Additionally, it is possible in the context of the present invention to use a protective cover layer such as tempered glass or chemically strengthened glass, to enhance durability and scratch resistance.

[0053] According to a preferred embodiment of the present invention, the coating composition on the transparent conductive layer is specifically designed in order to keep the friction coefficient of the outer surface low at a pre-determined level. Thus, the coating composition comprises materials having a low coefficient of friction. The materials of the coating composition may be selected from the list comprising, polytetrafluoroethylene (PTFE) or other fluorinated polymers such as polyvinylidene fluoride (PVDF), fluoroelastomers, perfluoroalkoxy (PFA), ethylene tetrafluoroethylene (ETFE). Fluorinated polymers are a class of synthetic polymers that contain fluorine atoms in their molecular structure. These polymers are characterized by the presence of carbon-fluorine bonds, which impart unique and desirable properties such as high chemical resistance and exceptional thermal stability. These properties make these polymers a good selection for the coating layer because being highly resistant and withstanding high temperatures is desired properties for the touchscreen. Besides these properties, for the object of the present invention having a low coefficient of friction is specifically important. Among the fluorinated polymers polytetrafluoroethylene (PTFE) is the most preferred because in addition to high resistance to chemicals, good mechanical properties and thermal stability, it also has a very low coefficient of friction.

[0054] In a preferred embodiment of the present invention, ultra high molecular weight polyethylene (UHMWPE) is used for the coating composition of the outer layer.

[0055] It has been found out that when ultra high molecular weight polyethylene (UHMWPE) and polytetrafluoroethylene (PTFE) are used together in the coating composition, the outer layer has a low friction coefficient as well as having the most desired properties in terms of mechanical stability, low surface energy and thermal stability. Thus, it has been found out that according to the present invention, there is a synergistic effect when using ultra high molecular weight polyethylene and polytetrafluoroethylene together in order to form the coating compotion of the outer layer. There is the same or similar synergistic effect in varying degrees when ultra high molecular weight polyethylene (UHMWPE) is used together with any one of the fluorinated polymers.

[0056] According to a preferred embodiment of the present invention, the resulting coefficient of friction of the coating layer should be lower than 1 .0. According to a more preferred embodiment, the coefficient of friction should be between 0.5 to 1.0. According to the most preferred embodiment the coefficent of friction is lower than 0.5 and preferably it is 0.4 or even lower. According to an embodiment of the present invention the friction coefficient is at most 0.2.

[0057] In order to impart the desired coefficient of friction values according to the present invention, ultra high molecular weight polyethylene (UHMWPE) and a fluorinated polymer selected from the list of fluorinated polymers is used either alone or in combination. According to a most preferred embodiment, ultra high molecular weight polyethylene (UHMWPE) and polytetrafluoroethylene (PTFE) are used together in the composition of the coating layer.

[0058] In a preferred embodiment of the present invention the coating composition comprises 70 to 85% by weight of ultra high molecular weight polyethylene and 15 to 30% by weight of polytetrafluoroethylene (PTFE).

[0059] In another embodiment of the present invention the coating composition comprises 60- 80% by weight of ultra high molecular weight polyethylene and 20 to 40% by weight of polytetrafluoroethylene (PTFE).

[0060] In a further embodiment of the present invention the coating composition comprises 50 to 85% by weight of ultra high molecular weight polyethylene and 15 to 50% by weight of polytetrafluoroethylene (PTFE).

[0061] Partitioned surfaces in the context of haptic technology and the present invention, refer to surfaces divided into distinct regions, each capable of providing different tactile feedback or haptic responses. This segmentation allows for more precise and varied tactile interactions, enhancing user experience and enabling more complex functionalities in various applications. This can be provided by physical and I or virtual segmentation wherein in the physical segmentation the surface is physically divided into separate regions, each with its own haptic actuators or mechanisms. It is also possible to form grids of ITO cells. Each finger has to be stimulated with a different and independent tactile signal. In order to demonstrate the concept of true multi-touch haptic interactions by physical segmentation, a surface capacitive touch screen is ablated using a UV laser to pattern a grid of conductive indium tin oxide (ITO) cells and thin ITO wires carrying electric current to the cells for independent electrostatic actuation. In the virtual segmentation, there are software-defined regions on a single continuous surface where different haptic responses can be simulated.

[0062] Thus, another important aspect of the present invention is the localized haptic feedback which refers to the precise and targeted delivery of tactile sensations to specific areas of a device or interface, allowing users to receive physical feedback directly under their fingertips or in particular regions.

[0063] According to the present invention an effective method is employed where transparent films such as polyvinylidene fluoride (PVDF) films can be utilized to generate localized haptic feedback on touch displays. Furthermore, the optical transparency feature of the film actuators provided design flexibility, since they can be mounted in any shape and at any location on the touch interface. To demonstrate this, 50 pm thin PVDF films are positioned beneath a transparent plastic plate that can be mounted on a display. Unlike when using a stack of actuators, this achieved accurate localized haptic feedback using only single actuators. Indeed, stack actuators can have the disadvantage of reducing the transmittivity of light, thus affecting the visual quality of the display output. This drawback underscores the efficiency of the inventive method in delivering precise haptic sensations while simultaneously simplifying the overall design.

[0064] In order to test the inventive concept, two transparent touch interfaces were designed and constructed. They consist of transparent plastic plates and multiple transparent PVDF-film actuators (from PolyK Technologies, optical transparency > 90% at 300- 1000 nm wave- length) attached beneath the touch surface. Two different configurations were examined using analytical and experimental methods: (a) First, the modal analysis was performed in order to identify the proper characteristic parameters such as actuation frequency and vibration amplitude considering human- factors principles, (b) Afterward, these findings were utilized to evaluate subjects’ performances via experimental studies.

[0065] Multiple transparent PVDF-film actuators (20 x 20 x 0.05 mm) are attached to the bottom of a clear polyvinyl chloride (PVC) plastic layer (100 x 50 x 0.6 mm), which is constrained via a clamp mechanism along its rectangular perimeter. The PVDF films are ITO-coated on both surfaces. Coatings have a sheet resistance of about 200 Q / sq, which means the thickness of an electrode is approximately 5 nm (the resistivity of ITO is ~10-4 Q cm). To ensure fixed boundary conditions, the plastic plate is clamped between two metal frames using several nuts and bolts on the sides. The structure stands on a 10-inch PC monitor, which is placed horizontally on a desk. Vibration isolation between the structure and the monitor is provided with a 1 cm thick foam rubber.

[0066] Unipolar analog input signals are generated by a 32-bit microcontroller (STM32F407G). An executable program is developed in Unity software to communicate with the micro-controller and convey indicators of the randomized signals. At the same time, the choice responses of the subjects are recorded via an interface. A custom-designed amplifier circuit with adjustable gain amplifies the unipolar signals and excites PVDF-film actuators. It hosts a high-pass filter stage to eliminate DC components originating from the microcontroller. Hence, pure sinusoidal high-voltage signals are obtained on the amplifier output. Finally, the excitation voltage is directed to the relevant actuators by a multi-channel relay module, which is controlled by the microcontroller board, as well. To ensure proper connection with transparent actuators, electrically conductive adhesive tapes are utilized. In case of incomplete connectivity silver paste is applied.

[0067] PVDF-film actuators are glued (clear epoxy adhesive) to the plate in such a way that the positive electrodes are positioned directly beneath the layer. Hence, to prove the safety of the interface, electrical breakdown for the utilized PVC plate must be investigated. The dielectric strength of the PVC material is about 25 kV / mm: breakdown voltage = dielectric strength x thickness = 25 kV / mm x 0.6 mm = 15 kV Since operating excitation voltages are below 300 Vpp, the setup is safe to conduct human experiments.

[0068] For the experiments, two identical touch interfaces with different actuator configurations are prepared. In the first configuration, two actuators are mounted on the right and left sides, respectively. The second configuration consists of 8 actuators, which are mounted in a 2 x 4 array formation. Both configurations are arranged symmetrically with respect to the origin of the surface geometry (Figure 1 ).

[0069] To perform finite element analysis (FEA), the governing piezoelectric equations including the charge coefficients matrix are derived from various reliable sources ensuring accurate representation in the program. In addition, the required coefficients of the elastic compliance matrix are obtained from experimental studies. Consequently, the basic properties of the utilized PVDF material are given in Table 1 .

[0070] Table 1. Basic physical parameters used in the FEM analysis.

[0071] First, modal analysis of the touch interface is performed to be able to determine the suitable frequency values which will be used to validate the design experimentally. Then forced-vibration analysis is performed to find out the generated out-of-plane displacements and to show the feedback localization.

[0072] The structures for A / B configuration and array configuration are built and simulated in COMSOL Multiphysics finite element analysis program. The only differences between the 2 configurations are the number and the arrangement of the PVDF actuators. Every actuator is attached beneath the PVC layer with their entire surface and materials are assigned to geometries accordingly. After performing a modal analysis on the entire structure, the first natural frequencies turned out to be coni = 451.2 Hz for the A / B configuration and coni = 454.2 Hz for the array configuration, respectively (Figure 2). The slight variation in the values is because of the configuration difference.

[0073] According to basic modal analysis principles, each of the natural frequency values corresponds to a definite and distinctive mode shape of the structure. So, natural frequencies must be avoided in order to generate localized vibrations at desired locations successfully. Thus, the frequency of the operating voltage must be far enough from the first natural frequency. In addition, it should also be situated in the perception interval for human skin which can reach up to 800-1000 Hz. Considering those design limitations, 5 frequency values are selected. As explained hereinafter, these values will be used to determine the frequency where the human fingertip is most sensitive to vibrotactile haptic cues.

[0074] The spacing between those frequency values should be at least as large as the Weber fraction to be able to convey significantly different stimuli to subjects. This difference between the frequency values is based on the Weber’s rule which states that as the intensity of a stimulus increases, the magnitude of the change needed to detect a difference also increases proportionally. In other words, the just noticeable difference (JND) between two stimuli is a constant fraction (Weber fraction) of the stimulus intensity. The Weber’s rule can also be applied to vibration frequency and Weber fractions are mostly clustered around 15% - 30%. So, 5 frequency values equally spaced (30%) on logarithmic scale are selected: 137, 178, 230, 300 and 390 Hz.

[0075] Basically, the forced-vibration analysis is performed to determine the response of a mechanical system to a time-varying input. Considering this particular embodiment of the present invention, this input is the periodically changing strain generated by the PVDF actuators and the response is out-of-plane displacement obtained on the plate surface. In order to compare the effect of frequency change, it is necessary to normalize the displacement values at each frequency. This allows for a direct comparison of the impact of frequency in human experiments while eliminating the influence of other factors. Afterwards, the frequency value where the human fingertip exhibits the highest sensitivity and the detection threshold of the skin for vibrotactile cues will be identified. In the first configuration, both actuators are excited with a pure sinusoidal signal of 100 V peak-to-peak amplitude and with 5 selected frequencies. Individual excitation of the PVDF-based actuators provides the localization of the vibration where the generated displacement amplitude reaches 0.36 pm, 0.37 pm, 0.39 pm, 0.45 pm and 0.63 pm depending on signal frequencies, respectively (Figure 3). Those displacement amplitudes are higher than the absolute detection threshold for the human fingertip reported in literature. Choi and Kuchenbecker reported the minimum threshold to be less than 0.1 pm. Particularly, Verrillo found that the absolute threshold for vibration detection is approximately 0.06 pm at around 250 Hz, which holds true for both men and women.

[0076] Since the entire structure (the geometry and the positioning of the actuators) is symmetrical with respect to the origin, the vibration patterns observed when only actuator-B is excited are identical to those observed when only actuator-A is excited. Hence, they are omitted to save space. Additionally, it appears that the vibration pattern of the 390 Hz signal is starting to become pervasive to some degree, likely due to its relative proximity to the first natural frequency (451 Hz, see Figure 2a), because as stated hereinbefore, mode shapes are vibration patterns occurring at natural frequencies. However, it can still be considered localized.

[0077] In the second configuration, each actuator is activated individually with 230 Hz sinusoidal signal (amplitude is 100 Vpp again). This frequency value demonstrating the highest sensitivity for vibratory cues has been determined based on the results of the human experiment conducted in the A / B configuration. Meanwhile it lies in the range of 200-300 Hz where the human fingertip is reported to be perceptually most sensitive to vibratory cues according to several studies. Additionally, it is necessary to determine the displacement magnitudes, similar to the case for the A / B configuration.

[0078] As expected, the vibration maps formed by individually exciting actuators A, D, E, and H are almost identical in terms of shape and displacement magnitude (Figure 4). Likewise, the individual activation of the remaining actuators (B, C, F, and G) leads to the formation of similar vibration maps but with increased displacement magnitudes. These equivalences among the corner-actuators and among middle-actuators are based on the structural symmetry with respect to the origin. Obviously, the displacement magnitudes obtained in the array configuration are different from those in the A / B configuration since the positioning of the actuators have changed. Generally, the closer they are located to the boundaries the lower is the generated displacement.

[0079] Here, it is important to state that forced-vibration analysis performed using FEA program provides convincing evidence of distinct and prominent vibration patterns on the corresponding actuators, solidly proving the effectiveness of achieving localized haptic feedback (Figure 4).

[0080] The primary objective of the first experiment is to characterize the haptic interface by assessing and analyzing the key actuation parameters considering human factors: actuation frequency and detection threshold. For this, one of the classical psychophysical methods introduced by Fechner is used to estimate the absolute threshold value for detection: repeated-measures, within-subject method of constant stimuli. It is accomplished with the one-interval, two-alternatives, forced-choice (1 1- 2AFC) paradigm since it can provide more objective psychophysical procedures.

[0081] Here, one interval (11) refers to the presentation of one detectable stimulus in each trial. In other words, both alternatives are presented concurrently in every single trial. And two alternatives (2A) means that two alternatives of stimuli are present in the experiment. The forced-choice (FC) paradigm is a commonly used method in psychophysics, wherein participants are presented with alternatives and required to choose the one where they perceive a detectable stimulus. It is important to note that participants are not allowed to withhold their response or choose not to respond. The term 2AFC is often misused to describe a yes-no task, which involves presenting a stimulus randomly in some trials and not in others. In a yes-no task, the observer responds after each trial with either "yes" or "no." However, the results of a yes-no task are more susceptible to various response biases compared to 2AFC tasks. For instance, in the case of extremely low tactile stimuli, a person may truthfully respond "no" (indicating they did not perceive any vibration) on every trial, while the results of a 2AFC task would demonstrate the person's ability to reliably determine the location (A-side or B-side) of the same extremely low tactile stimulus. In the study, the subjects are presented with two haptic stimuli, one generated by the actuator the other being no stimulus at all. Their task is to determine which side, A or B, corresponds to the presence of haptic feedback. Eight subjects (four female, four male) with a mean age of 28.9 years took part in the experiment. All of them were right- handed and used the index finger of their dominant hand in the experiment. They did not report any sensorimotor impairment.

[0082] After some preliminary observations, 50 V is predicted to be the required voltage amplitude at 230 Hz to produce vibratory feedback at absolute detection threshold. Taking 50 V as the center value, 4 lower and 4 higher amplitudes of excitation voltage are added to the stimulus set which are equally spaced on logarithmic scale: 17 V, 22 V, 29 V, 38 V, 50 V, 65 V, 85 V, 110 V, 143 V. Considering Weber’s rule, the spacing between amplitude values is once again selected as 30%. This approach was previously explained.

[0083] The simulation outputs of the forced-vibration analysis for the A / B configuration have revealed that the excitation at each selected frequency produces similar vibration patterns, though with different displacement amplitudes (Figure 3). So, the activation voltages are adjusted to eliminate the frequency effect and equalize the displacement amplitudes using proper gain coefficients (Table 2).

[0084] 137 Hz 178 Hz 230 Hz 300 Hz 390 Hz

[0085] Maximum Displacement

[0086] Amplitudes at 100 VPP

[0087] Gain Coefficients for

[0088] Normalization

[0089] Table 2. Variation of vibration displacements with different frequencies

[0090] For example, the amplitudes of the stimulus set are modified for 137 Hz:

[0091] 1.08 * [17, 22, 29, 38, 50, 65, 85, 1 10, 143] = [18, 24, 31 , 41 , 54, 70, 92, 1 19, 154]

[0092] The touch interface designed has a rectangular shape since lateral motion is the most effective method to explore the surface properties. Before the experiment, subjects were informed about their tasks and instructed to interact with the haptic interface as they would with a typical smart device equipped with a touch display. They were trained for approximately 3 minutes to become familiar with the haptic feedback effects generated by the touch-screen interface. In the training session, they were exposed to each stimulus twice (1 for each alternative side) at 230 Hz. In the experiment session, every subject conducted a set of 180 trials (9 stimuli) for each of 5 signal-frequency levels, a total of 900 trials. Hence, each stimulus appeared 20 times (10 times on A- side and 10 times on B-side). Those appearances were randomized block-wise: each stimulus was given once before any stimulus was given twice. This method helps to reduce the learning and carry-over effect and to increase statistical validity. The subjects’ task was to determine the side with the haptic feedback on it and to select it with a mouse located next to the monitor (Figure 5a). To put it differently, they were exposed to the question: “where do you feel tactile feedback, A-side or B-side?”. When they made the selection, the next trial was originated by the software immediately. The experiment for one subject lasted about 70 minutes. The background image (Figure 5b) displayed on the monitor under the transparent haptic interface serves to demonstrate the optical transparency of the touch surface. Similarly, it is placed on a colored paper to emphasize optical transparency (Figure 6).

[0093] In the second experiment, a multiple-choice procedure is designed to prove the ability of the touch-screen interface to provide localized haptic feedback. Here, the subjects try to detect the one with haptic feedback out of 8 locations: A, B, C, D, E, F, G, and H (Figure 7).

[0094] 230 Hz is set to be the operating frequency for the pure sine signal. Because according to the results of the human experiments with the A / B configuration, it was turned out to be the critical member of the frequency set where the fingertips of the participants are most sensitive to vibratory feedback. Two amplitudes are selected from the voltage stimuli set: one is the next greater one to the absolute detection threshold (65 V), and the other one is the highest level (143 V). Previous simulation results have shown that the generated displacement magnitude is higher when one of the actuators in the middle (B, C, F, or G) is actuated compared to the case when one of the actuators in the corners (A, D, E, or H) is actuated (Figure 4). To compensate for this difference caused by the location effect, the gain coefficient 2.45 / 2.15 = 1 .13 is used to increase the excitation voltage of the corner actuators.

[0095] Additionally, the difference caused by the configuration of the actuators must also be eliminated. According to the finite element analysis results, two different configurations have led to maximum vibration magnitudes of 0.392 pm and 0.245 pm on the corresponding actuators at 100 Vpp and 230 Hz, respectively (Figure 3 and 4).

[0096] According to our findings in finite element analysis (FEA) program, we observed a direct correlation between the excitation voltage and displacement amplitude of the generated vibration which can be demonstrated as linear functions (Figure 8). So, the maximum displacement amplitudes produced in A / B configuration at 65 V and 143 V are 0.25 pm and 0.56 pm, respectively. To obtain the same displacement amplitudes in the array configuration, the excitation signals with voltage amplitudes of 106 V and 232 V shall be used.

[0097] Six subjects with a mean age of 27.5 years participated in the experiment which was conducted over two sessions. Before the experiment, subjects underwent a 4-minute training process. They were asked to explore the touch surface freely and to identify the specific location with the highest perceived haptic effect out of the eight available options with the mouse next to the monitor. In the training session, two different haptic cues (with amplitudes of 106 V and 232 V) appeared on each different location twice. In the experiment session, both signals are conveyed to each location 20 times. So, the experiment consists of totally 320 trials per participant. After each trial, the subject's response triggered the sub-sequent trial, in which haptic feedback stimuli were randomly delivered to different locations. Again, the stimuli are randomized block-wise. The multiple-choice experiment is completed approximately in 40 minutes.

[0098] Results of the First Experiment

[0099] Success rates are averaged among 8 subjects for each stimulus value (9 voltage levels) and data points of psychometric functions for 5 different frequencies are obtained (Figure 9). The dashed curve indicates the ideal psychometric function in 2- AFC condition. Since there are 2 choices it starts from the value of chance performance 0.5 and the threshold is defined as the point at which the participants achieve 75% correct responses. This threshold value is equivalent to a 50% threshold in a psychometric function derived from a yes / no detection experiment. As depicted in the graph, the overall performance of the subjects improves as the stimuli amplitudes increase. However, the curve corresponding to 390 Hz exhibits an unexpected anomaly in the highest two stimuli, potentially attributed to the pervasive behavior of the vibration pattern at that specific frequency. Participants appeared to encounter ambiguity during the decision-making process, particularly when the haptic effect was discernible not only on the intended target area but also close to the other side (Figure 3e). As anticipated, the participants' performance yielded the most favorable outcomes at 230 Hz and 300 Hz.

[0100] Absolute detection threshold results are analyzed using two-factor ANOVA with repeated measures. The null hypothesis of a significant effect was rejected when the resulting p-value was found to be less than the predefined significance level of a = 0.01. In our case, the null hypothesis states that varying amplitude and frequency of the excitation signal does not affect the perception performance of the subjects. The results show that it is rejected (p<0.01 ) for both factors which means that amplitude and frequency independently have a significant effect on success rates of the participants. Moreover, there is no significant interaction effect between two factors (p>0.01 ). In other words, the effect of one factor on the success rate does not depend on the levels of other factor which is consistent with the parallel behavior observed in the psychometric curves for each frequency.

[0101] Ogive curves (Sigma-shaped or S-shaped curves) are fitted to the data points, with the threshold representing the stimulus level at which detection occurs in 75% of the total trials. If the threshold values fall between two stimuli, a simple linear interpolation process is employed. Required excitation voltages to achieve vibration displacement amplitudes of detection threshold are calculated and given below (Table 3):

[0102] Table 3. Variation of required voltages for detection thresholds with different frequencies.

[0103] The data tabulated above are plotted and the obtained graph exhibits a U-shaped threshold characteristic, which aligns with the findings reported in the literature (Figure 10). This threshold characteristic verifies those findings that the sensitivity of the human skin on the fingertip increases as the stimulus frequency increases up to approximately 200 Hz, and it diminishes as the stimulus frequency surpasses 300 Hz. Among 5 different and equally-spaced frequency values utilized in this study, it is observed that the skin’s detection threshold for vibratory cues is minimized at 230 Hz. Including additional frequency values would likely exhibit a consistent pattern with the trend depicted in the plotted graph.

[0104] Results of the Second Experiment

[0105] Success rates of the participants for each of the 8 locations for two different voltage amplitudes are plotted in the bar charts below (Figure 1 1 ). Those voltage amplitudes are represented by color bars: the blue bars correspond to the low voltage (106 V) and the red bars correspond to the high voltage (232 V). Bars start from 50% of success rate since the lowest one among all subjects is 55% (Subject-2 at location B). This proves that even the vibration displacement of 0.25 urn is to some extent sufficient to perceive the haptic feed-back and the results are consistent with the findings reported in previous studies. With only a few exceptions, every subject showed improved performance across all 8 locations when actuators are excited with higher voltage (232 V) compared to with low voltage (106 V). Furthermore, two participants exhibited the best performance at higher voltage, achieving 100% accuracy among all locations.

[0106] When the hit rates were averaged for each participant, it was observed that all of them exhibited a clear improvement in the success rate at the high voltage (Figure 12).

[0107] Besides the performance metrics of the individuals, the general accuracy of locationbased responses is also important. To demonstrate this, confusion matrices are plotted for both low- and high-voltage cases (Figure 13). The average performance of participants at low voltage does not drop below 74%, and it reaches at least 82% when the two lowest performances are excluded. At high voltage, the average performance is significantly improved, reaching a success rate of 91 % at the worst-performing location, location-G. Indeed, the average performance score at all locations for the entire touch interface is 95.8%. In both cases, the lowest performances are observed when the C- and G-actuators are actuated, which could be attributed to structural deficiencies such as poorer coupling of the actuator to the surface or interference caused by neighbor actuators.

[0108] In addition, average success scores at the corner locations (A, D, E, H) consistently rank among the top 4 or 5 in both cases because these actuators have fewer neighboring actuators that can potentially interfere with their haptic effects compared to the middle locations. Eventually, when the two lowest performances at locations C and G are excluded, the average performance at every location reaches a minimum accuracy of 95%, which can be considered a very good score.

[0109] In conclusion, the concept of transparent localized haptics in this study is introduced via two different arrangements: A / B- and array configuration. In the first configuration two actuators are mounted on the left and right sides of the rectangle plate. The finite element analysis method is employed to simulate the structure and obtain information about relevant design parameters such as the frequency and amplitude of excitation signals and the generated amplitudes on the interface. Among the selected frequency set, 230 Hz is the frequency where the detection threshold for vibrotactile cues is at its minimum (34.3 dB re 1 Vpp). As expected, the human fingertip sensitivity represents a U-shaped curve: amplitude thresholds increase when the frequency is lower or higher than 200-300 Hz. Because the skin on the human fingertip is most sensitive to vibratory feedback within the interval of 200-300 Hz. Similar findings have been reported in numerous previous studies as well.

[0110] The second configuration consists of 8 actuators arranged in a 2x4 matrix formation and is designed to demonstrate the capability of generating localized haptic feedback on desired locations. The actuation frequency of 230 Hz is chosen based on the supportive findings from the first experiment. Two excitation amplitudes, 106 and 232 volts are selected: they generate maximum vibration displacements of 0.25 pm and 0.56 pm on the second setup, respectively. The success rates are averaged among 6 subjects and 8 different locations, resulting in an accuracy of 83% at low voltage and 96% at high voltage.

[0111] Hence, the results, especially at higher voltage, strongly validate the localization process of the generated haptic feedback on touch displays, enhancing the overall user experience. Considering that the maximum amplitude used in this study is 232 V, it is evident that utilized transparent PVDF-based materials are suitable actuators for achieving localized and rich haptic effects since they are able to handle excitation ranges of up to 5000 V. Here, it is worth mentioning again that the touch interface is composed of a 0.6 mm thick PVC layer, and higher voltage levels would be necessary to generate comparable detectable haptic cues on a stiffer surface, such as glass. Besides, PVDF actuators allow the possibility to increase the voltage to higher levels and to construct a stack (2-3 fold) of PVDF actuators without compromising much on transmittivity.

[0112] In addition, an amperemeter is employed with a resolution of 1 mA to estimate the power consumption of the proposed touch interface in array configuration. When applying a voltage amplitude of 70 Vrms at 230 Hz to all eight actuators simultaneously, the amperemeter consistently displayed zero current. This observation indicates that the current drawn by each individual actuator is less than 0.125 mA, resulting in an instantaneous power consumption of each actuator of less than 17.5 mW. It is important to note that with a more sensitive measurement device capable of detecting microampere-level currents would result in a significantly lower power consumption calculated. Our estimation aligns with the findings reported in a study published by D’Anniballe et al. In that study, they applied a sinusoidal electric field of 15 MV / m (f = 0.1 Hz) to a PVDF actuator with a size of 62x13 mm and a thickness of 50 pm. They observed a current draw of an amplitude of 2 pA, leading to an instantaneous power consumption of 1 .88 mW.

[0113] Although the application process of the actuators to touch surface poses challenges, this study serves as a good proof of the concept. In alternative embodiments microfabrication methods can be employed to produce touch interfaces with higher haptic resolution. It is important to note that a comprehensive vibration analysis will always be necessary in order to effectively implement this in real-life applications.

[0114] A brief explanation of the drawings:

[0115] Figure 1. Scaled versions of actuator-configurations: (a) A / B Configuration; (b) Array Configuration.

[0116] Figure 2. First mode shape of the structure: (a) Mode shape for the A / B configuration; (b) Mode shape for the array configuration.

[0117] Figure 3. Forced vibration analysis outputs when only the left actuator is excited at: (a) 137 Hz; (b) 178 Hz; (c) 230 Hz; (d) 300 Hz; (e) 390 Hz.

[0118] Figure 4. Forced vibration analysis outputs show localized vibration patterns on corre- spending locations only: (a) Actuator-A is excited; (b) Actuator-B is excited; (c) Actuator- C is excited; (d) Actuator-D is excited; (e) Actuator-E is excited; (f) Actuator- F is excited; (g) Actuator-G is excited; (h) Actuator-H is excited.

[0119] Figure 5. (a) Experimental setup designed for the first experiment; (b) The original background image displayed on the monitor.

[0120] Figure 6. The transparent interface on color paper in A / B configuration

[0121] Figure 7. (a) Experimental setup designed for the second experiment; (b) The original background image displayed on the monitor.

[0122] Figure 8. Generated vibration displacements at 230 Hz with two different configurations.

[0123] Figure 9. Psychometric curves obtained in A / B configuration.

[0124] Figure 10. Variation of mean detection thresholds with different frequencies.

[0125] Figure 11 . Success rates in array configuration at low voltage (blue bars) and at high voltage (red bars): (a) Subject-1 ; (b) Subject-2; (c) Subject-3; (d) Subject-4; (e) Subject-5; (f) Subject-6.

[0126] Figure 12. Average values with standard error bars.

[0127] Figure 13. Confusion matrices for 8 locations: (a) At low voltage; (b) At high voltage.

[0128] Several different embodiments according to the present invention are defined herein below:

[0129] A haptic interface device comprising: a housing configured to be grasped or worn by a user, comprising one or more sensors configured to detect user inputs or interactions with the device, control electronics being coupled to the one or more sensors, the control electronics configured to:

[0130] - receive input signals from the one or more sensors;

[0131] - process the input signals to determine a preset tactile feedback response;

[0132] - generate output signals based on the determined tactile feedback response; and

[0133] - transmit the output signals to produce tactile feedback corresponding to the determined tactile feedback response, and a tactile surface being connected or positioned on at least a part of a surface of the housing in such a manner that the tactile surface is configured to interact with the user's sense of touch, wherein the tactile feedback comprises one or more of force feedback or motion sensations, and wherein the tactile surface is a touchscreen having a coefficient of friction lower than 1.0 comprising, a substrate as the base layer, a transparent conductive layer, a dielectric layer beneath the transparent conductive layer, and a coating layer incorporated over the transparent conductive layer.

[0134] According to another embodiment, the housing of the haptic interface device further comprises at least one actuator and a mechanical interface configured to transmit the tactile feedback produced by the at least one actuator to the user. In a further embodiment, the control electronics of the haptic interface device is further coupled to at least one actuator and the control electronics is configured to transmit the output signals to the one or more actuators to produce tactile feedback corresponding to the determined tactile feedback response wherein the tactile feedback comprises one or more of force feedback, vibrations, or motion sensations.

[0135] In a different embodiment, the substrate as the base layer is produced from glass and / or plastic materials, wherein the glass materials can be selected from a list comprising soda lime glass, aluminosilicate glass and gorilla glass and the plastic materials can be selected from a list comprising polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyimide, polyethylene naphthalate.

[0136] In a further embodiment the substrate as the base layer is produced from glass polymer composites or ceramics such as aluminum oxide.

[0137] In another embodiment the transparent conductive layer is made from indium tin oxide (ITO). According to a preferred embodiment, the thickness of ITO is 250 nm.

[0138] In a preferred embodiment, the coating layer comprises a coating composition comprising fluorinated polymers selected from the list comprising, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), fluoroelastomers, perfluoroalkoxy (PFA), ethylene tetrafluoroethylene (ETFE).

[0139] In another embodiment, the coating composition further comprises ultrahigh molecular weight polyethylene (UHMWPE). In a still further embodiment, the coating composition comprises polytetrafluoroethylene (PTFE) and ultrahigh molecular weight polyethylene (UHMWPE) such that the friction coefficient of the tactile surface is lower than 0.4.

[0140] According to a different embodiment, the coating composition comprises from 70 to 85% by weight of ultrahigh molecular weight polyethylene and from 15 to 30% by weight of polytetrafluoroethylene (PTFE).

[0141] In another embodiment the coating composition comprises from 60 to 80% by weight of ultrahigh molecular weight polyethylene and from 20 to 40% by weight of polytetrafluoroethylene (PTFE).

[0142] In a further embodiment the coating composition comprises from 50 to 85% by weight of ultrahigh molecular weight polyethylene and from 15 to 50% by weight of polytetrafluoroethylene (PTFE).

[0143] In a different embodiment, the transparent conductive layer has a thickness from 10 nm to 500 nm.

[0144] In a further embodiment, the coating layer has a thickness of less than 1 micrometers.

[0145] In a preferred embodiment, the coating layer comprises a coating composition comprising an ultrahigh molecular weight polyethylene (UHMWPE) such that the friction coefficient of the tactile surface is lower than 0.04.

[0146] In another embodiment the coating composition further comprises polytetrafluoroethylene (PTFE).

[0147] According to a preferred embodiment, the ratio of polytetrafluoroethylene (PTFE) to ultrahigh molecular weight polyethylene (UHMWPE) is 2:1 to 9:1 .

[0148] According to another preferred embodiment, the surface capacitive touch screen is physically partitioned with a grid pattern of conductive indium tin oxide (ITO) cells and thin ITO wires carrying electric current to the cells for independent electrostatic actuation.

[0149] According to another embodiment, the surface is physically divided into separate regions, each with its own haptic actuators.

[0150] Haptic feedback mechanisms according to the present invention may be selected from, vibration motors being small motors that create vibrations in specific regions of the surface; electroactive polymers being materials that change shape or texture when an electric field is applied; ultrasonic waves wherein ultrasonic vibrations are used to create a sense of texture or friction on a smooth surface; piezoelectric actuators being materials that deform when an electric current is applied, creating tactile sensations.

Claims

CLAIMS1 . A haptic interface device comprising: a housing configured to be grasped or worn by a user, comprising one or more sensors configured to detect user inputs or interactions with the device, control electronics being coupled to the one or more sensors, the control electronics configured to:- receive input signals from the one or more sensors;- process the input signals to determine a preset tactile feedback response;- generate output signals based on the determined tactile feedback response; and- transmit the output signals to produce tactile feedback corresponding to the determined tactile feedback response, and a tactile surface being connected or positioned on at least a part of a surface of the housing in such a manner that the tactile surface is configured to interact with the user's sense of touch, wherein the tactile feedback comprises one or more of force feedback or motion sensations, and wherein the tactile surface is a touchscreen having a coefficient of friction lower than 1.0 comprising, a substrate as the base layer, a transparent conductive layer, a dielectric layer beneath the transparent conductive layer, and a coating layer incorporated over the transparent conductive layer.

2. The haptic interface device according to claim 1 wherein the housing further comprises at least one actuator and a mechanical interface configured to transmit the tactile feedback produced by the at least one actuator to the user.

3. The haptic interface device according to claim 2 wherein the control electronics is further coupled to at least one actuator and the control electronics is configured to transmit the output signals to the one or more actuators to produce tactile feedback corresponding to the determined tactile feedback response wherein the tactile feedback comprises one or more of force feedback, vibrations, or motion sensations.

4. The haptic interface device according to anyone of claims 1 to 3 wherein thesubstrate as the base layer is produced from glass and / or plastic materials, wherein the glass materials can be selected from a list comprising soda lime glass, aluminosilicate glass and gorilla glass and the plastic materials can be selected from a list comprising polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyimide, polyethylene naphthalate.

5. The haptic interface device according to anyone of claims 1 to 4 wherein the substrate as the base layer is produced from glass polymer composites or ceramics such as aluminum oxide.

6. The haptic interface device according to anyone of claims 1 to 5 wherein the transparent conductive layer is made from indium tin oxide.

7. The haptic interface device according to anyone of claims 1 to 6 wherein the coating layer comprises a coating composition comprising fluorinated polymers selected from the list comprising, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), fluoroelastomers, perfluoroalkoxy (PFA), ethylene tetrafluoroethylene (ETFE).

8. The haptic interface device according to claim 7 wherein the coating composition further comprises ultrahigh molecular weight polyethylene (UHMWPE).

9. The haptic interface device according to claim 8 wherein the coating composition comprises polytetrafluoroethylene (PTFE) and ultrahigh molecular weight polyethylene (UHMWPE) such that the friction coefficient of the tactile surface is lower than 0.4.

10. The haptic interface device according to claim 8 wherein the coating composition comprises from 70 to 85% by weight of ultrahigh molecular weight polyethylene and from 15 to 30% by weight of polytetrafluoroethylene (PTFE).1 1 . The haptic interface device according to claim 8 wherein the coating composition comprises from 60 to 80% by weight of ultrahigh molecular weight polyethylene and from 20 to 40% by weight of polytetrafluoroethylene (PTFE).

12. The haptic interface device according to claim 8 wherein the coating compositioncomprises from 50 to 85% by weight of ultrahigh molecular weight polyethylene and from 15 to 50% by weight of polytetrafluoroethylene (PTFE).

13. The haptic interface device according to claim 6 wherein the transparent conductive layer has a thickness from 10 nm to 500 nm.

14. The haptic interface device according to any one of the preceding claims wherein the coating layer has a thickness of less than 1 micrometers.

15. The haptic interface device according to anyone of claims 1 to 6 wherein the coating layer comprises a coating composition comprising an ultrahigh molecular weight polyethylene (UHMWPE) such that the friction coefficient of the tactile surface is lower than 0.04.

16. The haptic interface device according to claim 15 wherein the coating composition further comprises polytetrafluoroethylene (PTFE).

17. The haptic interface device according to claim 16 wherein the ratio of polytetrafluoroethylene (PTFE) to ultrahigh molecular weight polyethylene (UHMWPE) is 2:1 to 9:1 .

18. The haptic interface device according to claim 1 , wherein the surface capacitive touch screen is physically partitioned with a grid pattern of conductive indium tin oxide (ITO) cells and thin ITO wires carrying electric current to the cells for independent electrostatic actuation.

19. The haptic interface device according to anyone of claims 1 to 17, wherein the surface is physically divided into separate regions, each with its own haptic actuators.

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