OPERATION OF A TELEVISION APPARATUS
A television can be basically divided into two parts, namely: the first one dedicated to the reception and the second charge of producing the image and sound. The basic operation of a TV has not changed much in recent years but the components are used, many of them now being integrated circuits.
Production of the image. TV signal
Once we understand the operation of the cathode ray tube as an essential element for the imaging, we will see electronic devices which make possible the formation of moving images on the screen of television.
The most logical is to analyze how a television signal, ie, how they form and what features it has. The transmission of color television signal basically consists of four distinct stages: the first is obviously capturing a real image using a camera suitable for it.The video signal to transmit the image information and sound In this process, the light from outside is broken down into three components: red, blue and green. Next is to convert light rays captured by the camera into electrical signals called "Video". After obtaining video signals are sent to the receiver by some form of modulation. Finally, we must send each signal to its corresponding barrel, that is, the signal from the red light component will be sent to red canyon, and so do the signals from the blue light component and the component green light from the image to be reproduced. Parallel to this process is the transmission of the signal light component corresponding to the black-white image, in order to be displayed also in black and white monitors who are not prepared for reproduction in color. Currently there are several systems used to perform the transmission of video signals, such as NTSC, PAL or SECAM .. However, all will be compatible with each other because, otherwise, would be quite uncomfortable, if not unfeasible, the marketing of television where they could only reproduce images captured by the system. The same happens with the TV in color should occur with black and white. There must be a full compatibility to view images captured in black and white on a color monitor and be able to view images captured by a system of color in a black and white monitor, although obviously in the latter case, the images will be seen in black and white. The idea, therefore, is that the information contained in the video signal must be identical in color and black and white as well as profitable in both types of receptor. The color signal, called "chroma signal or chromium," will be used only in the recipient of color, while white and black, called "video luminance signal" will be used both in color monitors and in white and black.The video signal is broken into three different signals: red, green and blue Each signal is sent to its corresponding barrel Once the signal has been achieved through a video camera to be sent to a TV receiver that can be reproduced. This is accomplished by modulating a signal with it much more often called radio frequency carrier. This modulation is a modulation in amplitude. This signal is received by the receiver circuit, which is built on the same TV. Application of the video signal to T.R.C. Once collected by the receiver signal is amplified by a "video amplifier." After amplification of the signal is passed to implement the TRC. Without any signal applied to the cathode of CRT, it would be about 160V or so. The grid itself is at a lower voltage, because the grid is negative with respect to the cathode.The black signal stops the flow of electrons towards the screen If the signal received by the TRC is for a black, it will be a high voltage, since the camera dark tones produce high voltages. When high voltage is applied to the TRC, this will increase the tension over the 160V. This increased tension will cause the grid is more negative with respect to the cathode and therefore fewer electrons pass through the tube. Passing fewer electrons will have fewer crashes on the screen and therefore the phosphor screen will not emit much light. This results in a dark spot on the screen. These signals inform the receiver that it has finished transmitting a full screen and therefore now proceed to issue a new screen, starting again for the top corner.