SPEAKERS/MONITORS/PROJECTORS

Loudspeakers and headphones

• Digital data is sent from the computer to a Digital to Analogue Converter (DAC) where it is converted into an analogue signal
• The signal is then boosted using an amplifier and finally sent to a speaker

Amp = amplifier 

LCD Monitors 

• Liquid Crystal Display (LCD) screens contain groups of red, green, and blue diodes to form each pixel
• Monitor screens require backlighting using Cold Cathode Fluorescent Lamps (CCFL) or LEDs since the crystals act as a light valve and do not emit light themselves

LCDs have an actual diode across the screen and that has to be ‘warmed up’- it takes a while for it to fully turn on and reach full brightness

CCFLs versus LEDs

• Using LEDs to back-light LCD screens has a number of advantages over the older CCFL technology:
• They reach their maximum brightness almost immediately
• The image is sharper with more realistic and vivid colors
• They produce a brighter light which leads to better picture definition
• Since LEDs are very small, this allows the screens to be much thinner in construction
• They last almost indefinitely which makes the screens much more reliable
• They consume very little power and therefore produce very little heat as well as reduce running costs

Advantages of LED:

• They reach their maximum brightness almost immediately
• They consume very little power and therefore produce very little heat as well and reduce running costs
• More reliable than CCFL because maintenance is less compared to ccfl
• The image is sharper with more realistic and vivid colours
• They produce a brighter light which leads to better picture definition
• Since LEDs are very small, this allows the screens to be much thinner in construction
• They last almost indefinitely which makes the screens much more reliable
• They consume very little power and therefore produce very little heat as well and reduce running costs
• More reliable than CCFL because maintenance is less compared to ccfl 

Advantages of CCFL:

• It’s more cost-effective

Disadvantages of CCFL:

• YOU NEED THE BARS/ TUBES so the screens can’t be thin- unlike LEDS

Advantages of OLED:

• OLEDs generate their own light so there is no need for the complexity of backlighting
• Much less power is consumed; this has a clear advantage when producing screens for battery-operated devices (e.g. mobile phones, tablets and smartwatches); it also means little heat is produced (reducing fire risks) and running costs are also reduced
• They have a larger field of view than LCD screens – and this is further enhanced when the screen is curved
• OLED screens are more flexible whereas LED are not 

Disadvantages of OLED:

• OLED screens suffer from what’s known as burn-in 
• OLED LED is always on, over, it will be burned in on the side of the screen 

What is a Colour depth image?

The number of bits determines the number of colors you can represent 

2^n  n = bit 

How many color combinations can u show with 8 bits? 

= 2^8 = 2^4 * 2^4 = 256

Projectors

What is the difference between normal DLP and short-throw projectors? 

• Short-throw projectors are more effective in confined spaces 
• DLP projectors can represent higher contrast 
• DLP projectors are cheaper because they use old technology, however, light is less visible on the projector 
• Short-throw projectors have better quality and the lighting of the room doesn’t affect the projection 
• DLP has better color accuracy, however, does suffer from rainbow light trails or afterimages if it’s only a 1 chip projector. 

Laser Projectors

• Laser projectors are able to represent the projected images over shorter distances- and can create bigger-sized images compared to DLP
• Laser projectors last longer and have a superior efficiency compared to LED. They have an overall high efficiency and last longer.
• Another thing would be when you turn it off, it turns off immediately. Whereas DLP takes a while to turn off- still using electricity so not as effective 
• Laser projectors still use a dlp, LCD, or LCOS chip but its light source is laser-based instead of light-based. 
• Therefore, laser projector is by default better than dlp, LCD, or LCos due to its utilization of laser tech instead of lamp technology.