Braille line
A braille display is an electronic device that allows the output of content in braille code from another device, to which it has been connected, allowing a blind person or person with low vision to access the information that it makes it easy for you. Some sites may refer to braille displays as braille displays.
Braille displays tactilely display information that a "screen reader" would. For this reason they are useful for blind people and especially for deafblind people.
Braille displays are made up of a set of cells, each with six or eight dots, that allow braille characters to be displayed. The dots, unlike printed braille, can toggle between up and down positions, so they can vary dynamically.
Using a braille display
The reading in a braille line is the same as that of printed braille, the difference is that it only reads on one or several lines that are updated. To do this, the points can go up or down depending on the characters or symbols that must be represented at all times.
Braille displays are made up of cells arranged in one or more rows so that the person using the braille display must read from one side to the other and press a button for the display to update.
In computers, a braille display is usually attached under the keyboard so that it is quick to change from one peripheral to another.
Six and eight points
Some braille displays contain cells of only six dots. These devices use conventional braille. These lines are used for people who do not want to learn eight-dot braille. Braille displays typically include eight-dot cells. In this way they can represent both six- and eight-dot braille.
Other functions
Braille displays often include a set of buttons that give them added functionality. In addition to the buttons for updating the content, you can find buttons to change the line or paragraph, which allow you to move through the texts quickly without having to resort to other keyboards.
Operation
Braille dots
A braille display is made up of several cells with six or eight small metal cylinders that either protrude from the surface through a hole or lie below the surface. An electro-mechanical mechanism allows the cylinders to go up and down, forming the Braille characters of the text to be read, with each cell being equivalent to a letter, a number, etc. The upper end of the metal cylinders is rounded to facilitate their detection without causing discomfort to the reader's finger, allowing the finger to slide through the successive points of the line.
Connection types
Older braille displays often use the serial line or parallel cable for connection to the computer or other peripherals. These devices have the disadvantage that they must be connected with the computer turned off.
Today, braille devices already use the most common connections in current computer equipment, such as the USB cable and Bluetooth. This has allowed them to be applied to other types of devices such as mobiles and PDAs.
Transmission of information to the braille display
Braille displays, like other peripherals, need a driver to be used. This driver is usually the same or similar to the one used in screen readers.
This is connected within a succession of drivers that receive the information that the screen sends to it. Each of the drivers performs a series of operations with it and then passes the information received to the next driver.
In this way several devices can be used simultaneously. For example, the information can be received by the screen reader, which takes the necessary data and reads it, and then the magnifier driver takes the image of the screen and enlarges it, sending only the part of the image to the graphics card driver. the screen to be displayed.
Where do you get the information from?
The braille display can work in several ways, depending on whether we are in a text or graphic environment.
In shell environments, the line only has to render in braille the characters that are displayed on the screen.
In graphical environments it is necessary to add more information. Braille displays and screen readers can easily access text and menus, but other components are more difficult to interpret. For this reason, APIs usually allow programmers and interface designers to add information to their window components that allows it to be read by this type of program and device.
For example the tag "<img>" to put images in HTML code, which is used in web pages, includes the "alt" attribute, which allows you to give a description (not visible, unless the link to the photo is broken) that serves to give a description to the blind person.
<IMG src = "…" alt = "Wikipedia logo">
It is highly recommended that programmers and designers add this type of information, giving clear and descriptive information to the people who use these media.
Keep in mind that the information should be consistent with the content and should not dedicate itself to describing what is already obvious (for example, saying "this is a button"), nor go too far of information that may slow down and/or make the use of the applications by the blind user slower and/or more difficult.