Braille displays

Gu W., Chen H., Tung, Y.C., Meiners, J.C., and Takayama, S., Multiplexed hydraulic valve actuation using ionic liquid filled soft channels and Braille displays, Appl. Phys. Lett, 90,033505-033508, 2007. 

Y. Kato, T. Sekitani, M. Takamiya, M. Doi, K. Asaka, T. Sakurai, and T. Someya. Sheet-type Braille displays by integrating organic field-effect transistors and polymeric actuators. leee Transactions on Electron Devices, 54(2) 202-209, Feb 2007. 

Lee S, Jung K, Koo J, Lee S, Choi H, Heon J, Nam J, Choi H (2004) Braille display device using soft actuator. Proc SPIE 5385 368... 

Ren K, Liu S, Lin M, Wang Y, Zhang QM (2007) A compact electroactive polymer actuator suitable for refreshable Braille display. Proc SPIE 6524 65241G... 

Bar-Cohen Y (2010) Refreshable braille displays using EAP actuators. EAPAD 2010 Proc SPIE 7642 764206-1-764206-5. doi 10.1117/12.844698... 

Gu W, Zhu XY, Futai N et al (2004) Computerized microflnidic cell culture using elastomeric channels and Braille displays. Proc Natl Acad Sci USA 101 15861-15866... 

Because polypyrrole operates in aqueous electrolytes at room temperature, the largest niche for conjugated polymer microactuators is biomedical applications. Commercialization efforts are underway for blood vessel coimectors, a valve to prevent urinary incontinence, and a Braille display [25,122,133]. One area that requires further research is the temperature-dependence of actuator metrics, because for biomedical applications the devices must be operated at 37°C. In PPy(DBS) microactuators, strain increases from room temperature to body temperature by 45%, and they are 250% faster, but the blocked force drops [126]. 

However, the power of any particular screen reader is in the degree to which the other capabilities dictated by the use of the GUI are achieved. The fundamental differences in the ways that a text-only command-line interface (CLI) and a GUI provide output to the video screen present access problems for persons who are blind. These are related to both the ways in which internal control of the computer display is accomplished and the ways in which the GUI is employed by the computer user (Boyd et al., 1990). The CLI-type interfaces use a memory buffer to store text characters for display. Since all the displayed text can be represented by ASCII code, it is relatively easy to use a software program and to divert text from the screen to a speech synthesizer or Braille display. However, this type of screen reader is unable to provide access to charts, tables, or plots because of their graphic features. This type of system is also limited in the features that can be used with text. For example, features such as size, shape, and font or alternative graphic forms are not captured in standard ASCII text code. 

The actuation technology based on conducting pol3uners has opened interesting perspectives, so that the first commercial applications in the biomedical field, such as blood vessel connectors, Braille displays and cochlear implants, are being developed today [247]. 

For those with sight problems the University of Tokyo has developed a thin flexible polymer display where a system of Nafion polymer cantilevers pushes up 0.9 mm radius dots through a 10 pm polydimethylsilane membrane to a height of 0.25 mm above the display surface to form a Braille display. The thin flexible 1 mm thick bendable display is driven by a Braille input. The system is powered at 3 V which is sufficient to cause electro-osmosis which bends the cantilever by differential osmotic pressure. Removal of the voltage allows the cantilever to straighten up and though, theoretically the device can operate at up to 2 Hz, this is not physically possible with the installed organic transistor circuitry. The dots are displayed in a typical 2x3 dot Braille character array - the 4 cm prototype features four rows of six characters. 

Finally, a soft and smart device is fabricated by integrating the IPMC actuator with control and senor units. Recently, organic transistor control and sensor technologies have been developed. Hence, all organic, flexible electromechanical devices can be constructed using the IPMC and an organic transistor. In this chapter, such an example is described as a sheet-type Braille display. 

Figure 6.9 Images of a Braille display (a) the flexible Braille sheet display using IPMC actuator array (b) the device assembly (c) circuit diagram of the Braille sheet display (Reprinted with permission from Kato, Y., Sekitani, T., Takamiya, M. et al. Sheet-Type Braille Displays by Integrating Organic Field-Effect Transistors and Polymeric Actuators, IEEE Trans on Electron. Devices, 54 (2), 202-9. Copyright (2007) IEEE).

Figure 6.11a shows one of the Braille dots moving upwards and downwards. Four Braille letters displayed by the present device are also shown in Figure 6.1 lb. Someya et al. tested the readability of the sheet-like Braille display using the IPMC. Four visually impaired individuals participated in the reading tests. When the operator input Na and Wa in the Japanese Braille format, all four individuals were able to recognize the letters correctly. 

Yobas, L., Durand, D.M., Skebe, G.G., et al. (2003) A Novel Integrable Microvalve for Refreshable Braille Display System, J. Microelectromech. Syst., 12, 252-63. 

Kato, Y., Sekitani, T., Takamiya, M., et al. (2007) Sheet-Type Braille Displays by Integrating Organic Field-Effect Transistors and Polymeric Actuators, IEEE Trans.Electron Devices, 54, 202-209. 

Ren, K., Liu, S., Lin, M., Wang, Y. and Zhang, Q.M., A compact electroactive polymer actuator suitable for refreshable Braille display, (2007) Proceedings of SPIE Smart Structures and Materials 2007 Electroactive Polymer Actuators and Devices (EAPAD) (ed. Bar-Cohen, Y.), 6524, Gl-9. 

A Braille Display System for the Visually Disabled Using a Polymer Based Soft Actuator... 

In this research, a new type of dynamic Braille display is presented. It employs a dielectric elastomer for the basis of the tactile display. It is constmcted with a notably simple mechanical and electrical architecture. The proposed device is organized with a dual-layered array of tactile cells that generates vertical motion used to push up or down the Braille pins. These electrically driven tactile cells can generate either small-scale vibratory motion or linear displacement. They differ from conventional devices in softness and controllable compliance, cost effectiveness, simple manufacturability and high actuator density. Furthermore, the small size of the proposed concept enables the development of a high-density display device. 

In this chapter, in the Sections 23.2 and 23.3, the basic principle and design idea for the tactile cell is explained. The issues in the development of the Braille display device are discussed next (in Section 23.4) and then (in Section 23.5) exemplary feasible applications of the proposed tactile display are given. 

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