Video devices
Video devices can be divided into the following groups:
• TV sets (Televisions) or TVs with a device for recording and playing back images (TVs with VCR);
• devices for recording and reproducing the image (Videos) or devices used only for image reproduction (vi-deo players);
• devices for image processing and recording (video cameras) or having an additional possibility of its playback;
• video accessories, i.e. assembly tables and printers for video systems, lamps for video cameras and others.
Modern television equipment should be assessed by specifying the technical solutions used in it and its capabilities. Currently manufactured television sets can be classified taking into account the diversity of performance characteristics, that is, due to the:
• screen diagonal - a distinction is made between receivers with a small screen diagonal (into 42 Cm, i.e. up to 16"), medium screen diagonal (42-52 Cm, that is 17 -20″), large screen diagonal (52-88 Cm, that is 21 – 34″) and a very large screen diagonal (above 88 Cm, i.e. above 35″);
• format (Aspect ratio) screen - A distinction is made between receivers with classic screen aspect ratios < 1,5, measured by the ratio of screen width to its height and receivers with a screen horizontally extended by the format 16:9 (> 1,5);
• image emission method – receivers with a cathode ray tube are distinguished (CRT) normal or with black coating, with liquid crystal dispersion (LCD) and optical projection system;
• image reproduction frequency – a distinction is made between receivers that reproduce the image at a frequency 50 Hz and frequency 100 Hz;
• screen convexity – there are receivers with a convex screen (less and less often), vertical flat and super flat;
• colors of broadcast – on this basis, television sets are divided into color and black and white (currently practically not used);
• implemented functions, which may relate to vision or sound;
• housing – box enclosures are distinguished, generally made of plastic and intended to be placed on a cabinet or stand, and furniture enclosures, in which the TV set is an element of furniture construction, fulfilling functional or aesthetic functions.
Almost all currently produced TELEVISION sets are equipped with a remote control and programming system for many stations and are adapted to work with a VCR and video camera. Most of them are equipped with a teletext reception system and the possibility of receiving cable TV, also on Hyper-Band bands.
A modern VCR should be characterized by high image quality, high durability and reliability of elements, quietness and speed of the mechanism, easy handling and dust-resistant design. Currently manufactured VCRs use digital signal processing technologies, so that high-quality images are obtained, free from interference. The most important element of the VCR are the heads, that read the signal from the VCR tape. More heads for better write read quality. High-quality VCRs generally have four heads (4-Head). Position of the heads relative to the tape, for the best reading, it can also be intelligently automatically adjusted. The VCR should also adapt automatically to the system, in which the recording on tape took place and in which the image is to be reproduced. VCRs include a tuner, allowing you to receive a TV signal and save it, regardless of the connection to the TV set.
Video Cameras, depending on the model and manufacturer, they can work with cassettes of different formats: VHS-C, S-VHS-C, Video 8, Hi-8, Mini-DV and VHS or S-VHS. Video cameras allow you to enlarge the photographed objects using the optical and digital methods. Some types are additionally equipped with a side liquid crystal screen (LCD), as well as the ability to take widescreen photos in the format 16:9. Some camera models also have a photo mode for recording still shots. These cameras are also adapted to work with a computer. New opportunities for the development of this equipment resulted from the use of digital technology.