Computer monitor

Computer monitor

COMPUTER MONITOR – is an output device of the computer for text or graphic data to display.

The monitor can be of several types:

  • LCD Monitor
  • CRT Monitor
  • PDP Monitor

 

CRT (Cathode Ray Tube) monitors – is monitor type, in which phosphorescent screen is created by electron bunch (electrons formerly known as cathode ray). This monitor consists of a large vacuum bulb, in the end of which is a source of electron (current-heated filament). Electric and magnetic field created in the bulb speed up and focus to the fiber, which rapidly “runs” in the other side of the bulb of the screen surface.

The surface of the screen is covered with material from inside, which glows after the speed up electrons hit the surface. Electrons after hitting the glass, loose the energy radiate the harmful x-rays. Improving the design of the monitor, efforts were put to reduce the radiation, but still it is no 0. Monitors of a bigger size and colored ones radiate more, as the electrons must be speed up more. To direct and speed up the electrons, powerful electric fields are used, which also are harmful to the human health. The bigger screen, the more powerful the field.

Liquid crystal display (LCD) is a thin, smooth display, consisting of a number of color or monochrome pixels, set out against the source of light.  Liquid crystal monitors are popular in the portable devices, due to low power consumption, size and weight. In the colored monitors each pixel is divided into three cells (additional pixels), which used by the above filters are converted to red, green and blue.

Pixels can be controlled individually, in this way conveying the million of different tones in each of them. Older CRT monitors use the same methods to convey the color.

History

 

Color liquid matrix story begins in 1970. As usual, LCD technologies were oriented to the market of professional equipment. When the first generation technological matrix LCD manufacturing process was in progress and manufacturing costs became less, professional market for LSD monitors became too small the great breakthrough of LCD’s occurred only then when first portable computers appeared.

In particular, 1980-1990 this year is considered to be the year of portable PC revolution.  LCD matrixes that were produced were “Black and white” and colored, but they were “passive”.  These matrixes dealt well with the static images, but if there was need to show a certain motion, the image became spoiled and it was impossible to see and understand.  And this, of course, limited the appliance of this type of matrix in other spheres.

After a certain time, evolution of LCD matrix gave birth to a new active type of matrix (Active TFT LCD Display). “Active” matrixes were already able to convey moving objects on the screen, this tackled to the invention of first stationary LCD monitors for personal computers (PC). This type of monitors was very expensive, but users did not pay any attention to that. They just wanted to get rid of the old and huge CRD technology based monitors, that is why the demand for  the CRT monitors rose rapidly – the improvement of manufacturing technologies, gradually the characteristics of the matrix  got better, the diagonal of the monitors became bigger as well.

Health effects

The monitor radiation spread, electric, electromagnetic, electrostatic fields are harmful: central nervous system, eyes, heart, skin, and other internal organs. Facial skin lesion begins within a few hours of work with the computer. Clinical symptoms: itching, skin tension, edema and erythema.