Colour television
Colour television is the transmission and reception of images in full colour. The colour television system can produce programs both in colour on colour receivers and in black and white on monochrome receivers. Also, col-our receivers receive monochrome pictures when they are being transmitted.
Colour transmission contains two basic components - brightness information, and colour information.
Red, green and blue are the colours that are chosen for colour television.
In a colour camera an optical system separates the red, green and blue image components of a picture and concentrates these three components in separate but identical colour camera tubes. Thus, the output of one tube reacts to the red light image; another - to the green, and another - to the blue light image.
In a monochrome kinescope a single electron gun produces an electron beam. The brightness is controlled by an electron grid, which changes the electron beam density.
In a colour kinescope three electron guns produce three electron beams, which are synchronized. The intensities of beam are controlled by the voltage corresponding to the green, red and blue components respectively of the colour picture.
History of television
The principles of television aren't as complicated - or as modern - as you might think. TV technology has become more sophisticated than ever, but the basic method of sending a television picture is quite simple.
The idea of television originated in the later part of the nineteenth century. Many advances were made during the first half of this century, and television rapidly developed from a simple mechanical apparatus to its present form.
This was thanks to various electronic innovations, such as the thermionic valve and the cathode ray tube, which is used in both the receiver and TV camera.
The first live transmission was made by John Logie Baird, the TV pioneer, in 1924. By 1941 regular electronic TV transmission had begun in America, with the backing of the Radio Corporation of America, and television as we know it started.
It had come a long way since 1884, when Paul Nipkow of Germany patented a mechanical picture scanner. This system formed the basis for Baird's historic transmission.
Nipkow's invention depended on a rotating disc. Light passing through the holes in the disc was transformed into electric values by photosensitive cells. The path of each hole in the disc was different, and thus traced out a different line, and read the entire frame in a logical order.
At the receiving end, a lamp was used to send out corresponding impulses of light, which then passed through a further rotating disc, identical to the one at the transmitting end, and synchronized with it The light passing through the disc was projected onto a screen to recreate the original object
These attempts at televising objects were very crude, because the scanning speed was so slow - only twelve-and-a-half frames per second - and because the picture was composed of a mere 30 lines.
A comparable system is used today except that electronic scanning equipment is much faster: it is capable of readings 300,000 dots (the average number on a TV screen) in l/30th of a second. Approximately 25 frames per second are scanned.
Frame frequency is important in allowing television and films to create moving pictures. The eye retains an image for about l/16th of a second, so the mind experiences this succession of pictures as an uninterrupted flow. The large number of lines on modem televisions make clearly defined pictures possible.
The cathode ray tube, which is the central part of every TV, was first patented in 1897, by K.F.Braun in Germany. This is used, in its refined form, in present-day television sets. Its importance lies in its capacity to produce pictures.
The tube has a screen which glows when struck by a stream of electrons from an electron gun inside the tube. Each point of the screen emits more or less light according to how long the beam is aimed at it
A colour television has three electron guns - one for each of the primary colours, red, blue and green. They bombard a screen of phosphor dots, arranged in groups of three - one dot for each colour - while a masking device sorts the beams so each one falls on its allocated dot
A colour television camera also has three cathode tubes and electron guns.
АННОТИРОВАНИЕ
Аннотирование - это вторичная обработка письменной информации. Для того чтобы зафиксировать краткое содержание произведения, пишется аннотации Аннотация (Abstract или Summary) - это краткая справка о статье, патенте книге справочнике и т.п. с точки зрения содержания. При аннотировании печатный материал излагается в предельно сжатой форме. Это процесс свертывания (сжатия) информации с очень большим уменьшением по отношению к оригиналу.
Аннотации бывают описательные, Справочные, реферативные, рекомендательные и критические.
Описательная аннотация состоит из трех частей:
1; Справка к аннотации. В ней указываются следующие данные: автор название работы на английском языке, название издательства (для журналов - название, номер и год издания).
Основная часть должна отражать перечень наиболее характерных положений по содержанию работы.
Заключительная часть. В этой части должен быть общий вывод или указание на один какой-то вопрос, которому в работе уделено особое внимание, а также рекомендация, для кого данная работа может представлять особый интерес.
К аннотациям предъявляются следующие требования:
Лаконичность языка, то есть использование простых предложений (глаголы употребляются в настоящем времени в действительном или страдательном залоге).
Строгая логическая структура текста.
Обязательное введение в текст аннотации безличных конструкций, например: «Сообщается...», «Внимание уделяется ...», «Описываются ...» и др., С помощью которых происходит введение и описание текста оригинала.
Недопущение повторений в заглавии и тексте аннотации
Точность в передаче заглавия оригинала, отдельных формулировок в определений.
Основные штампы (Key-patterns) аннотаций
The title of the text (book, article) is...
The author(s) of the text (book, article) is (are) ...
The text (book, article) was published in ...
The text (book, article) is about...
5. The text (book, article) is devoted to...
6. The text (book, article) provides us some (certain, interesting, valuable) information on ...
7. In the text (book, article) much attention is given to...
The text (book, article) is addressed to the specialists in the field of…
It should be mentioned that…
a) In (=to) my opinion…
b) I suppose (that)…
c) I think (that)…