Which Monitor?, Monitor costs, Colour monitors

Which Monitor?

Monitor Size	Typical Viewing Distance

9˝

12˝

17˝

21˝

5´ 10´ 15´

Monitor costs

CCTV monitors may be free standing, suspended from a wall or ceiling, or rack mounted. Wall and ceiling mounts allow the monitor to be rotated and tilted for viewing from different angles.

Why does a 17-inch black and white CCTV monitor cost more than the equivalent black and white TV? The answer is that the CCTV monitor has specialist features and characteristics. For example, the average TV set has around 300 lines of resolution while the CCTV monitor would normally have over 700 lines. The CCTV monitor also has regulated power supply to maintain performance during power fluctuations, an isolation transformer and a fast acting automatic frequency control (AFC) loop to reduce radio frequency interference.

Colour monitors

Colour monitors are also available in a similar range of sizes. These monitors usually accept only composite colour signals, although where very high quality images are required, monitors with a Y/C (luminance and chrominance) input should be used.

Two principal types of colour CRTs are currently in use: the shadow mask CRT and the Trinitron. The face of the shadow mask type is based on the shape of a sphere, whereas the Trinitron is based on

the shape of a cylinder. This means that the Trinitron is curved only in the horizontal plane providing an image which is more geometrically accurate and which reduces operator eye-fatigue caused by reflected light from above. Close examination of the shadow mask CRT reveals how the image is constructed from dots or ellipsoids whereas the Trinitron images consist of continuous stripes resulting in a cleaner and more stable image.

For more information contact the Sony Business Information Centre: 01932 816340