8. Display Devices Flashcards
What should you do FIRST when a user reports taht the monitor is not working?
Check whether the monitor cable is plugged in
What should you FIRST suggest to a user if the user reports a blank screen on the monitor and you have verified that the monitor is plugged in
Suggest they check whether the monitor is switched on
What should a technician use to clean an LCD monitor screen?
User a paper towl or lint free cloth dipped in water, and wipe the screen gently
What is the purpose of the diffuser in a LCD display
It take the points of light and uniformly spreads them out over the entire area of the display
Which component of an LCD is responsible for converting the DC power back into AC?
Which component of an LCD display illuminates the display?
the backlight
What attaches to the LCD screen to allow the device to read any touch movements from the user, including swiping, pinching, touching, and other movement
a digitzer
Brightness
A measurement of the intesity of the engery output of a visibile light source with pure white having the maximim brightness and pure black the minimum bightness
Resolution
It is the number of pixels that make up the dimension of a display, represented in a ration value as the number of horizontal pixels b vertical pixels
Display Projector
A specialized computer display that projects an enlarged image on a large surface such as a wall, white board, or movie screen
DLP
Digital Light Processing
Digital Light Processing (DLP)
a technology that uses a single chip with a reflective surface composd of thousands of tine mirrors corresponding to individual pixels
LCD
Liquid Crystal Display
Liquid Crystal Display
A flat panel screen that uses a liquid crystal solution sandwiched between two polarizing filters and glass panels
Native Resolution
The fixed resolution for LCD or other flat planel display devices
Plasma Display
A device that contains a neon/xenon gas mixture sealed between two glass plates
Refresh Rate
the number of times in a second that a display hardware updates its buffer
TN
twisted nematic
Twisted Nematic (TN)
A liquid-crystal display consisting of nematic liquid crystal in a perpendicular orientation confinded between two plates of polarized glass
2 Prominent technologies for modern display devices
- LCD
- OLED
2 primary display technologies found in older devices
- Plasma
- CRT
OLED
Organic Light Emitting Diode
Organic Light Emitting Diode (OLED) Display
Flat planel screen that uses an organic substance a the semicondutor material in LEDs. Unlike LED, which uses an array of led bulbs, OLED uses a series of thin, light emitting films.
CRT
Cathode Ray Tube
Cathode Ray Tube (CRT) display
A display that continas a large vacuum tube with a flat end covered in phosphors. An emitter in the back shoots a steam of electrons at the phosphors to create an image
(Large and expensive)
Two technologies used to polarized the liquid crystals in a LCD
- Passive Matrix
- Active Matrix
Passive Matrix
- uses a grid of horizantal and vertical wires with an LCD element at each intersection.
- Each LCD element is a single pixel on the display
- Used by early LCD due to ease of manufacture
- slow refresh times, low contrast, poor support for higher resolutions
- Primarly used for small devices and industrial applications where their disadvantages aren’t a drawback
TFT
thin film transistor
Thin Film Transitor (TFT) LCD
Another name for Active Matrix LCD
Active Matrix Display
- Has a small transistor at each intersection which controlls the light for each pixel.
- Requires less current to control the pixels (which leads to better refresh rates)
- More expensive
- improved response rate and image quality
- Dominant display tech for PCs and mobile devices
The three ways of iluminative an LCD panel
- Reflective
- Transmissive
- Transflective
Reflective backlighting
- A mirror behind the pane bounced ambient light back to the user
- Cheap and power efficient
- diffucult to read without ample ambient light
- difficult to achive with TFT / active Matrix displays
- generally used with passive matrix
Transmissive
- A backlight behind the panel shines light towards the users, making the display readable in low light situations
- One drawback is that transmissive LCDs used in bright ambient light must have very powerful backlights
*
Transflective
- Uses both a backlight and a partially reflective layer between the backlight and the LCD display to capture ambient light.
- Allows them to operate efficiently under a wide range of lighting conditions
- Tend to be more expensive
Three common liquid-crystal technologies used in LCD displays
- TN (twisted Nematic)
- IPS (In-Plane Switching)
- VA (vertical alightment)
TN
twisted nematic
twisted nematic (TN)
- TN displays used nematic liquid crystal in a perpendicular orientation confined between two plates of polarized glass
- Most commong and oldest LCD panel type
- Advantages
- shortest response time
- low power draw
- high brightness when combined with LED backlighting
- low manufacturing cost
- Disadvantages
- very narrow viewing angel
- Common for low-end displays or for gaming displays or other applications where response time is important
IPS
In-Plane Switching
In-Plane Switching (IPS) display
- uses crustals which are horizontally aligned with the screen rather than vertically as in the TN LCD
- Allows the polarized crystals to move more freenly into the desired alinement
- Uses two transistors per pixel to impve the viewing angle (over the TN)
- Increases power consumption and decreases battery life in laptops
- Advantages
- Best viewing angles of all LCD displays
- ability to produe the most accurate colors
- Disadvantages
- increased power consumption and slower response time
VA
Vertical Alignment
Vertical Alightment (VA) display
- have crystals which are vertically aligned when there is no electrical current and horizantly aligned when current is applied
- The former blocks light, producing a black image
- The latter allows light from the backlight to pass through, producing a white image
- With VA, there is no twisting of the crytals, they are either horizontal or vertical
- Advantages
- Have bright whites and depp blacks
- Have wide viewings angles
- and good color production
- Disadvantages
- Have slower response times than TN or IPS
- typically more expensive
Four primary layers of an OLED display device
- Substrate which acts as athe structural framework. Red, green, and blue tinted plastic layers are added to substrate to produce color
- Anode: which draws electrons
- Cathode: which provides electrons
-
Organic Layer: which contains two sublayers
- conducting layer: in which the electrons move
- emissive layer (produces light)
Two important projector technologies
- LCD
- DLP
LCD projector
- An older technology that uses mirrors and prisms to direct light through LCD panels and towards the projector’s lens. Lamplight is projected through mirros and prisms which split the light up the primary colors of red, green, and blue
- Advantages
- Colors are more accurate
- Slightly sharper images than the DLP
- Producing a brighter image than DLP using the same wattage lamp
DLP
Digital Light Processing
Digital Light Processing (DLP) projector
- A newer technology that uses a single chip with a reflective surface composed of thousands of tiny mirrors corresponing to individual pixels.
- Projects color by passing the light from the lamp through a rotating wheel with red green and blue filters
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Advantage
- Smaller and more portable due to the user of the mirror chip instead of panels
- Produces deepr balcks than LCD, giving them a high contrast
- Less pixelation, allowing for smoother motion graphics
- Higther reliability due to fewer moving parts
Display features to consider:
- Analog or digital connection
- Aspect ratio
- Brightness
- Filters
- Refresh rate
- Resolution
Troubleshooting a blank display
- Verify the display has power
- Verify the display data cable is connected securely to both the display and the computer’s display port
- Use the Windows Advanced Boot meenu to boot into Safe Mode and check your resolution settings
- Verify your graphics card driver is compatible with your operating system. If not, obtain a compatible driver or replace the graphics card
- Use the device manager to check for problems with your graphics driver
- Use windows advance boot menu to boot into VGA mode to resintall or repair your display drivers.
- If you can see the initial boot screen when you turn on your comptuer, but it goes blank once windows starts to load, boot into safe mode and use system restore to repair windows.
