A Display Device is an output device to present information as visual.
The Display System is the final link between measuring process and the user. Display Devices are used in Instrumentation system to provide Instantaneous but non- permanent communication of information between a process or system and a human observer. Data can be presented to the observer in either an analog or in a digital form.
Display Devices are designed to project, show, exhibit or display soft copy information.
In measurement there are two types of displays Analog and Digital.
1. Analog display devices:
Analog Displays use a niddle and calibrated scale to indicate the values.
Analog displays have a pointer which moves over a graduated scale. They can be difficult to read because of the smallest scale division. For example the scale in the picture has 10 small divisions between 0 to 20, so each small division represents 2°C. The reading is therefore 32°C. The analog meter can show any value between 30°C to 32°C but we are unable to read the scale more precisely than about half a division.
2. Digital display devices
- Digital displays show the measured value as digit and they are more accurate than analog display. They are easier to use because they give specific value.
Digital displays are often capable of displaying smaller values in easy understandable way.
Types of Displays
Generally there are diffident types of displays but the most commonly used are
- Cathode Ray Tube (CRT)
- LED Display
- Liquid Crystal Display (LCD)
- Plasma Display (PD)