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02 February 2008

computer-controlled Braille output / reading devices

from Wikipedia:

A refreshable Braille display or Braille terminal is an electro-mechanical device for displaying Braille characters, usually by means of raising dots through holes in a flat surface. Blind computer users who cannot use a normal computer monitor use it to read text output. Speech synthesizers are also commonly used for the same task, and a blind user may switch between the two systems or use both at the same time depending on circumstances.

Because of the complexity of producing a reliable display that will cope with daily wear and tear, these displays are expensive. Usually, only 40 or 80 Braille cells are displayed. Models with 18-40 cells exist in some notetaker devices.

On some models the position of the cursor is represented by vibrating the dots, and some models have a switch associated with each cell to move the cursor to that cell directly.

The mechanism which raises the dots uses the piezo effect of some crystals, where they expand when a voltage is applied to them. Such a crystal is connected to a lever, which in turn raises the dot. There has to be a crystal for each dot of the display, i.e eight per character.

The software that controls the display is called a screen reader. It gathers the content of the screen from the operating system, converts it into braille characters and sends it to the display. Screen readers for graphical operating systems are especially complex, because graphical elements like windows or slidebars have to be interpreted and described in text form. Modern operating systems usually have an Application Programming Interface to help screen readers obtain this information, such as MSAA for Microsoft Windows or AT-SPI for GNOME.

A new development, called the rotating-wheel Braille display, was developed in 2000 by the National Institute of Standards and Technology (NIST) and although a second rotating display was designed at the Leuven University in Belgium[1] both wheels are still in the process of commercialization. Braille dots are put on the edge of a spinning wheel, which allows the user to read continuously with a stationary finger while the wheel spins at a selected speed. The Braille dots are set in a simple scanning-style fashion as the dots on the wheel spins past a stationary actuator that sets the Braille characters. As a result, manufacturing complexity is greatly reduced and rotating-wheel Braille displays will be much less expensive than traditional Braille displays.

History

The base of a refreshable braille display is a pure braille terminal. There the input is performed by two sets of three keys plus a space bar (as in the Perkins Brailler), while output is via a refreshable braille display consisting of a row of electromechanical character cells, each of which can raise or lower a combination of six round-tipped pins. Other variants exist that use a conventional QWERTY keyboard for input and braille pins for output, as well as input-only and output-only devices. In 1951, David Abraham, a woodworking teacher at Perkins, created a portable braille terminal.[2]

Braille computer monitor

The Braille computer monitor has rows and columns of rectangular cells. The cells include four rows and two columns of dots that can be felt for interpretation by the user. "The pins are driven by electromechanical impact drivers and are held in position by resilient elastomeric cords. The impact drivers are carried on a bi-directional printhead which travels beneath the movable pins. An erasing mechanism is provided to positively drive the pins downwardly to erase the characters produced by the printhead." [1] The Braille computer monitor is under the United States Patent 6700553 [2].

5 comments:

Anonymous said...

Dear Gentlemen:

Sorry, your device few Hungarian people can afford, therefore I should like to ask You whether You would be interested in the creation of a cheaper version.

Kind regards:

George Geeza Farkas
(ecofarkas@yahoo.com)

Vleeptron Dude said...

Szervusz George!

Are you in Pest? or Buda? (Or Somewhere Else?) Planet Vleeptron doesn't get a lot of e-mail from Hungary.

Okay, now please do not begin with nationalistic self-pity. My guess is most blind and vision-challenged people in the USA who need a machine like this cannot afford it, either.

Contrary to what you may have heard, our streets are not filled with gold -- and our benevolent government is not exactly a Loving Mother bestowing subsidies and gifts of health, medicine and assistance to those who need it.

(Translation: The USA is the only Western industrial nation which does not have free government universal medical care.)

I am very happy the Socialist Heroes have left Hungary (I saw these Kaloshnikov-carrying gangsters in Praha), maybe they can make their Paradise for American Workers now.

Okay, about a Plan to invent and create a cheap computer-controlled Braille reader machine ...

I like it!

Maybe you have been drinking a little too much Tokay, because you seem to think I am some kind of inventor genius like Edison or Nikola Tesla or Charles Proteus Steinmetz.

34 years ago I studied 1 year of electrical engineering. At that time, we were all excited about the New Invention: the Transistor! My computer was a Slide Rule. (Batteries not included.)

But I will do my best.

It seems to me the $$$$ secret is the basic individual "dot" element.

There is a hint that some of these modern machines do not use old servo electromechanical technology, but use piezoelectric crystal rods which expand and shrink by the presence or absence of an electrical signal -- crystals that grow and shrink from electric voltages.

I will try to find out who manufactures these piezo things, and how $$$$$ or $ (expensive or cheap) they are.

Köszönöm szépen for the very interesting Research Project! Please let me know your thoughts about these things. I am

Bob
Massachusetts USA
bobmerk@earthlink.net

P.S. Your e-mail has made me very sad that I have not been to Europe in a few years. And I want to see Budapest SO BADLY!!! The food is TERRIBLE here in the USA!

comprar un yate said...

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muebles en zamora said...

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www.teruel-3d.com said...

It cannot really have success, I suppose so.