Magnetic haptic printing technologyNTT Communication Science Laboratories

Magnetact magnetic haptic technology is a haptic interface technique that presents a variety of tactile stimuli in a very simple configuration. Only two magnetic rubber sheets are needed for the haptic presentation. The detailed magnetized pattern on the sheets creates the feeling of an uneven surface when rubbing sheets together despite the fact that they are flat surfaces. Toys, books, and other haptic products are expected to develop on a wide scale because the magnetic patterns can be easily altered to create a variety of bumps, the haptic interfaces do not require electricity, and the texture is retained for a long period of time once written to a sheet.

Traditional haptic interfaces can be categorized as "information display" types which use motors, speakers, ultrasound, and electromagnetic force, or "material" types which involve touching shapes and textures using paper, resin, or metal. Both types have advantages, such as dynamic control and functional scalability with the former, while the latter offers low maintenance costs because they do not require electricity or wiring. On the other hand, displays involve the challenge of the complexity of equipment, and materials are not scalable to change the haptic experience.

But our research has made it possible to print magnetic patterns on the surface of magnetic rubber sheets, which are very common materials, to control the texture, and create a material that can display information that combines the best of both worlds. In particular, one of the major triumphs of this study is the fact that magnetic patterns can create multiple haptic interfaces and selective haptic interfaces.

• Simple magnetizing technique creates detailed patterns to provide functions including haptic interfaces with intensity changes and selective haptic interfaces
• Magnetic patterns can design specific texture size and intensity
• Use to create haptic interfaces like picture books and toys that combine function and convenience

• Add texture to books and toys: Magnetic patterns are permanent after printing. Create haptic picture books with art and textures that can be carried around and enjoyed anywhere, and stored on a normal bookshelf.
• Turn large surfaces into low-cost haptic interfaces: Simply attach magnetic sheets to floors, walls, furniture, or props to create a sense of texture for specific objects like shoes, gloves, or tools.
• Haptic DIY lets users design textures: The familiarity of the material and simplicity of the construction make this a great tools for creating haptic content.

When two magnetic rubber sheets with the same patterns are stacked, the South and North poles on each sheet create attractive and repulsive forces between the sheets. These vertical forces feel like lateral or propulsive forces against the fingers that are trying to move the magnetic sheet. When these horizontal stresses are clustered, humans experience a tactile illusion phenomenon that feels like bumps. This research uses this illusion to create a sense of texture. This provides a sensation of bumpiness using a sheet that is actually flat.

The location, orientation and size of the bumpiness is determined by the magnetic pattern printed on the sheet, allowing for design of multiple textures. The relative ratio of attraction/repulse between the South and North poles can be calculated from the pattern pitches and relative position of the sheets, so the spatial frequency and intensity of the texture can be calculated easily.

By using this, when one piece of magnetic sheet A is rubbed over different magnetic sheets B, C and D, the intensity and size of the textures on each sheet can be completely different. It can also be designed as a selective haptic interface, where texture is only sensed when magnetic sheet A is matched with A, and magnetic sheet B is matched with B.

NTT Communication Science Laboratories - Human Information Science Laboratory