"Haptic feedback device"

Technical Field

The present application describes a haptic feedback device based on electroactive polymer structure.

Background art

Presently, most of the known state of the art technology on sensorial field is related with the use of thin film or electroactive polymer / piezoelectric structures applied in touchscreen user interfaces or peripherical devices for computer control (keyboards, etc.).

Some known applications refer to haptic feedback integrated in the textile structures, but in the vast majority they are implemented by means of embroidering methods. Some of the existing haptic feedback devices are based on rigid materials, generally metallic based, which implies the integration of these devices in rigid substrates, finding very low compatibility with textile-based solutions.

This disclosure aims to fulfil this state-of-the-art development flaw, allowing to achieve a seamless integration of haptic feedback devices over flexible textile products, with particular relevance on artificial leather applications, and with particularly low weight and thickness.

Summary

Present invention discloses a haptic feedback device for automotive interior surfaces characterized by comprising an artificial leather article with a front and back surface; a printed haptic device; and an insulation membrane; wherein the printed haptic device is physically integrated in the back surface of the artificial leather application, and the insulation membrane is located over the printed haptic device to ensure the integration in the artificial leather article and protect the printed haptic device.

In one of the proposed embodiments of present invention, the printed haptic device comprises at least a dielectric layer; and at least two electrode layers.

In another embodiment of the invention, the dielectric layer is arranged between the two electrode layers.

Yet in another embodiment, the dielectric layer comprises at least four printed piezoelectric layers arranged over substrate.

Yet in another embodiment, each electrode layer comprises at least two printed layers arranged over a substrate.

Yet in another embodiment, the substrate comprises a thin and flexible polymeric layer.

Yet in another embodiment, the insulation membrane comprises a highly flexible polymeric layer.

Present invention also discloses a method for integration of a haptic feedback device on an artificial leather application characterized by comprising the steps of: printing a piezoelectric haptic device; lay out in a sandwich arrangement, from top to bottom, an artificial leather application, the printed piezoelectric haptic device and an insulation membrane; submit the sandwich arrangement simultaneously to a pressure range between 3 to 4 bars and to a temperature range between 130°C to 160°C for a time period of at least 30 seconds.

In one of the proposed embodiments of present method the printing of the piezoelectric haptic device comprises the steps of: printing a first electrode layer; printing a piezoelectric layer over the printed first electrode layer; and printing a second electrode layer over the piezoelectric layer.

Yet in another embodiment of the disclosed method, the printing of the piezoelectric layer comprises the steps of: screen-printing a layer of polyvinylidene difluoride - trifluoroethylene within a thickness range of 15pm to 80pm over a substrate; curing the printed layer at a temperature of approximately 130°C in a hot plate during a time period between 15 to 20min; sequentially repeating the screen printing of a layer and the curing the layer tree times.

Yet in another embodiment of the disclosed method, the printing of an electrode layer over and/or under the piezoelectric layer comprises the steps of: screen-printing a layer of PEDOT:PSS within a thickness range of 30pm to 60pm over a substrate; curing the printed layer at a temperature of approximately 110°C during an approximate time period of 10 minutes in a thermal oven; repeat the screen-printing of a layer and the curing of said layer.

General Description

The present application describes the development of textile structures with the integration of interactive surface devices, touchpad and feedback technologies. The main focus of present disclosure is related with the development of printed electronic devices on textile structures that will generate smart functionalities (touchpad, luminescent, haptic and audio feedback).

As above-mentioned, the developed haptic feedback device is seamlessly integrated on a flexible textile product. To assure this integration, the device is produced by a combination of printed electronics and traditional lamination processes, assuring both flexibility and adaptability of the devices to flexible base products. The integration of printed electronics in these substrates brings added value to the development of new products, allowing the upscaling of similar devices via roll-to-roll printing processes.

The present application describes a printed piezoelectric device processed by screen-printing, and integrated in artificial leather, keeping the flexibility and versatility properties of this base substrate. The device is used to generate and transfer haptic feedback to the user through vibration, introducing changes in the artificial leather article texture, being possible to adapt it to a seat, console or steering wheel.

An actuator device, based on electroactive polymers, and processed by screen-printing, is used to generate haptic feedback like vibration and/or change in texture sensation is described. The actuator device can be integrated/coupled to a textile structure and used in automotive applications for example. Some of the production processes utilized on the development of the proposed device comprise a wide range of materials from vibrating motors to electroactive materials.

Brief description of the drawings

For better understanding of the present application, figures representing preferred embodiments are herein attached which, however, are not intended to limit the technique disclosed herein.

Fig. 1 - illustrates the proposed printed piezoelectric haptic device structure (100). The reference numbers are related to:

1- Printed Piezoelectric layer / dielectric layer;

2- Printed electrode layer.

Fig. 2 - illustrates the proposed final haptic device integration (200). The reference numbers are related to:

3 - polymeric insulation membrane;

4 - artificial leather article;

100 - Printed piezoelectric haptic device.

Fig. 3 - illustrates a sideview / vertical cross-section of the final piezoelectric haptic device (100) proposed. The reference numbers are related to:

1 - Printed Piezoelectric layer / dielectric layer;

2 - Printed electrode layer.

Description of Embodiments

With reference to the figures, some embodiments are now described in more detail, which are however not intended to limit the scope of the present application. The present application describes a printed piezoelectric haptic device (100) processed by printing techniques and integrated in a leather article (4) or surface.

A sandwich design is used for printing the piezoelectric haptic device (100), which consists in a printed piezoelectric layer (1) between two printed electrodes (2). The printed piezoelectric layer (1) operates as a dielectric layer to obstruct the electrical contact between both parallel upper and bottom electrodes (2), also behaving as the active layer, being responsible for the tactile sensation reproduction to the user during the touch on the piezoelectric haptic device (100).

A polyvinylidene difluoride - trifluoroethylene (PVDF-TrFE) ink (Piezotech FC 20) is used in the printing of the piezoelectric layer (1), having a thickness within 15pm to 80pm. The piezoelectric layer (1) comprises four layers, printed sequentially in order to minimize the existence of pinholes in the film and promote a better contact / touch performance. In between each of the four layers of the piezoelectric layer (1), the film is cured at a temperature of approximately 130°C in a hot plate during a time period between 15 to 20min.

The four piezoelectric layers of the main piezoelectric layer (1), in one proposed embodiment, are printed using a screen printing process with polymer screen based on a 32x70 mesh (32 yarns/cm and 70 pm yarn diameter) Thus, the total overall thickness of the piezoelectric haptic device (100) is defined between lOOpm to 250pm, including the thickness of the printed electrodes (2) ranging from 30pm to 60pm with a sheet resistance within 5mQ/sq/mil to 25mQ/sq/mil. Both bottom and top electrodes (2) are obtained through screen printing resorting to the use of two layers of PEDOT: PSS ink (EL P 5010, Orgacon) on each electrode (2), being cured at an approximate temperature of 110°C for approximate time period of 10 min in a thermal oven. A 90x40 mesh (90 yarns/cm and 40 pm yarn diameter) is used as the main platform for the electrodes (2).

The piezoelectric haptic device (100) is printed in a flexible and thin substrate in order to obtain a final solution with the critical thickness properties. The mentioned thin substrates comprise the use of flexible polymeric materials as Polyethylene Terephthalate (PET) or Polyethylene naphthalate (PEN) or Polyimide, on a thickness range comprised between 50pm and 100pm. Furthermore, these polymeric materials are compatible and can be integrated into textile structures.

After the production of the piezoelectric haptic device

(100), its integration in the artificial leather (4) in order to obtain the haptic device (200) is achieved using a polymeric membrane (3) with a thickness below 50 pm. Said integration is achieved through a pressure and heat method, on a temperature range between 130°C and 160°C and within a pressure range of 3 to 4 bar during at least for 30 seconds. The integration occurs directly between the sandwich comprising the artificial leather article (4), the printed piezoelectric haptic device (100) and the polymeric membrane

(3), in order to ensure the correct fixation of the piezoelectric haptic device (100) to the artificial leather article (4). The application under these specific integration conditions ensures the correct fixation of the piezoelectric haptic device (100) to the artificial leather

(4) without compromising the mechanical, electrical, and chemical properties of the developed printed haptic device (100). Furthermore, the materials applied in this development were specifically chosen in terms of mechanical, electrical, thermal and chemical properties to ensure both the functionality of the final solution, but also the final looks of the artificial leather device.

With this integration method, a device with a thickness comprised between lOOpm and 250pm is ensured to be fully integrated in an artificial leather article (4), allowing a good and lasting fixation of the printed piezoelectric haptic device (100) to the artificial leather substrate (4), allowing the incorporation of seamless haptic structures, for example in automotive interiors.

One of the major advantages of the disclosed technological developed method and product lies also in the fact that the thin and highly flexible polymeric membrane (3), used in the haptic device (100) integration, also acts as an encapsulating layer that protects the printed piezoelectric haptic device (100), contributing to the protection and conservation of inks, preventing their deterioration over time, ensuring a lasting and durable product (200). The polymeric insulation membrane (3) used in this application achieved satisfying results in terms of artificial leather adhesion and integration, being submitted to different standard tests, namely heat shrinking, heat ageing, elongation (at 100 N), burning rate, ageing by light and Di Mattia fatigue tests. All these standard tests demonstrated that the membrane stays completely attached to the artificial leather article, fulfilling the requirements for the present application .

In another embodiment of the proposed invention, the piezoelectric haptic device (100) integration can also be obtained through the application of an adhesive solution to promote the fixation of the printed haptic touchpad (100) to the artificial leather (4). This alternative production method and product helps to add up some rigidity to the final product (200), guaranteeing the perfect adhesion and durability of the integrated solution.

The overall integration of this solution (200) also implies the integration of additional controlling electronics. The connections of the piezoelectric haptic device (100) to these electronics are performed resorting to the use of a seamless cable for example. In the end of this cable, a connector is attached and then connected to the controlling electronics.

Using piezoelectric haptic devices (100), the integration can and must be done in the backing of the artificial leather (4), keeping all the visual and texture properties of this material.

The final solution (200), after its integration, is a fully printed and highly flexible piezoelectric device in an artificial leather material. The flexibility and durability allow this invention to be applied in multiple parts of the automotive interior, for example seats, consoles, doors and panels.

Nevertheless, it is necessary to apply an electrical voltage in order to obtain a tactile sensation when touching the piezoelectric device. The electric voltage to apply is selected according to the final application as well as the frequency of the signal. The piezoelectric device operates in AC conditions.