Resolution refers to the density of the screen image. It is expressed as the number of dots or picture elements (pixels) across one line, multiplied by the number of horizontal lines. A 1024 x 768 VGA screen has 1024 pixels or dots across a line and 768 lines down. Higher resolution allows more information to be displayed on the screen, but demands more from the graphics card.
The horizontal scan rate, also known as line frequency, is measured in kilohertz (kHz) and is the number of lines that can be painted horizontally in one second. The values of these frequencies usually range from 30 to 120.
Also known as refresh rate or image frequency, the vertical frequency is defined as the number of times that the image on the screen is refreshed or re-drawn in a second and is expressed in Hertz (Hz). Vertical frequency can be roughly estimated by dividing the horizontal frequency by the number of lines in the resolution used. The difference between the calculated figure and the actual one depends on the time that the electron gun needs to get back to the starting position after drawing each line. Using a higher frequency reduces eyestrain through minimizing flicker and minimizing variations in the image brightness.
Dot pitch is the diagonal distance between two phosphors of the same color, and it is normally expressed in millimeters (mm). In aperture grille tubes the equivalent of dot pitch is the horizontal distance between the phosphor stripes. Images will have greater clarity when the dot pitch is smaller. Because of their differences, dot pitch and stripe pitch cannot be accurately compared.
In principle, convergence means the ability of the monitor to correctly align the red, green and blue components of an image on the screen. A white line on the screen consists of three colored lines: red, green and blue. If the screen does not have any convergence errors, the lines exactly overlay each other, and the resulting color is white. In case of convergence errors, separate red, green and blue lines can be seen, instead of one white line
Moiré is a natural interference phenomenon that appears on all color monitors. It can be seen as a regular, wavy distortion pattern. It is caused by interference between the shadow mask (or aperture grille) and the resolution used. You can also change the image size and resolution or you can use moire controls in the monitor to reduce moiré. However, moiré adjustment can slightly reduce picture sharpness.
Expressed in the unit Kelvin (K), the color temperature is a way of defining the white balance displayed by the screen. A color temperature of 9300 K is typical for computer screens. A cooler color temperature will give a slightly bluer white, while a hotter color temperature makes the white more red.
number of times that the image on the screen is refreshed or re-drawn in a second and is expressed in Hertz (Hz). Same as Vertical Frequnecy. Using a higher frequency reduces eyestrain through minimizing flicker and minimizing variations in the image brightness. VESA currently states that 85 Hz is the recommended refresh rate. High frequency is especially important when working with a white background.
A shadow mask is a plate positioned close to the internal face of the Cathode Ray Tube. The shadow mask is perforated to direct the electron beams to strike the phosphors on the screen.
There are three different types of shadow masks: aperture grill, dot-trio and slotted shadow masks.
The aperture grill tube is well suited to demanding high-resolution usage where high levels of sharpness and contrast are needed. For color graphics applications, the aperture grille technology is often favored for its high capacity color display. However, technical illustrators may prefer shadow mask technology for precision drawings. Slotted mask is a mixture of dot-pitch and aperture grill technologies.
This is a type of shadow mask used in Cathode Ray Tubes. Consisting of a large number of vertical wires positioned just behind the inside face of the tube, it channels the electron beams to hit the correct phosphor regions. One or two damping wires are fitted inside the tube to reduce the movement of the aperture grille wires. They can be seen in every aperture grille tube, in the form of very fine horizontal grey lines on the screen.