Display device for presentation of images, video, or text transmitted electronically
An
electronic visual display
is a
display device
that can display
images
,
video
, or
text
that is transmitted electronically. Electronic visual displays include
television sets
,
computer monitors
, and
digital signage
. They are ubiquitous in
mobile computing
applications like
tablet computers
,
smartphones
, and
information appliances
. Many electronic visual displays are informally referred to as
screens
.
Starting in the early 2000s,
flat-panel displays
began to dominate the industry, as
cathode-ray tubes
(CRT) were phased out, especially for computer applications. Starting in the mid 2010s, curved display panels began to be used in televisions, computer monitors, and smartphones.
Types
[
edit
]
There are various technologies used for electronic visual displays:
An overhead projector can be considered a type of electronic visual display.
Additionally,
CRTs
were widely used in the past and
microLED
displays are under development.
Classification
[
edit
]
Electronic visual displays present visual information according to the electrical input signal (analog or digital) either by emitting light (then they are called
active displays
) or, alternatively, by modulating available light during the process of reflection or transmission (light modulators are called
passive displays
).
Display mode of observation
[
edit
]
Electronic visual displays can be observed directly (
direct view display
) or the displayed information can be projected to a screen (transmissive or reflective screen). This usually happens with smaller displays at a certain magnification.
A different kind of projection display is the class of "
laser projection displays
", where the image is built up sequentially either via line by line scanning or by writing one complete column at a time. For that purpose one beam is formed from three lasers operating at the primary colors, and this beam is scanned electro-mechanically (galvanometer scanner, micro-mirror array)) or
electro-acousto-optically
.
Layout of picture elements
[
edit
]
Depending on the shape and on the arrangement of the picture elements of a display, either fixed information can be displayed (symbols, signs), simple numerals (7-segment layout) or arbitrary shapes can be formed (dot-matrix displays).
Emission and control of colors
[
edit
]
Colors can be generated by selective emission, by selective absorption, transmission or by selective reflection.
Color emission and control
|
additive mixing
primary colors
add up to produce white light
|
subtractive mixing
filters, dyes, pigments (e.g.printing) subtract (absorb) parts of white light
|
temporal mixing (additive)
e.g. rotating primary color filter wheel in projectors
|
spatial mixing
(additive)
closely spaced sub-pixels
|
spatio temporal color mixing
combined spatial and temporal mixing
[1]
|
|
arrangement of sub-pixels
for additive color mixing
see
sub-pixel arrangements 1
see
sub-pixel arrangements 2
see
sub-pixel arrangements 3
|
subtractive color mixing does not require special sub-pixel arrangements
all components (e.g. filters) have to be in the same path of light.
|
Examples:
stripe
delta-nabla
PenTile
arrangement, e.g. RGB+White
|
|
Addressing modes
[
edit
]
Each sub-pixel of a display device must be selected (addressed) in order to be energized in a controlled way.
Addressing modes (selection of picture elements)
|
direct addressing
each individual picture element has electrical connections to the driving electronics.
|
multiplexed addressing
several picture elements have common electrical connections to the driving electronics,
e. g.. row and column electrodes when the picture elements are arranged in a two dimensional matrix.
|
|
|
|
active matrix addressing
active electronic elements added in order to improve selection of picture elements.
- thin-film diodes (TFDs)
- thin-film transistors
(TFTs)
- amorphous silicon (a-Si)
- polycrystalline silicon (p-Si)
- monocrystalline silicon
|
passive matrix addressing
the nonlinearity of the display effect (e.g. LCD, LED)is used to realize the addressing of individual pixels in multiplex addressing. In this mode only a quite limited number of lines can be addressed. In the case of (STN-)LCDs this maximum is at ~240, but at the expense of a considerable reduction of contrast.
|
The matrix of active electronic elements can be used in transmissive mode of operation (high transmittance required) or a non-transparent active matrix can be used for reflective LCDs (e.g.
liquid crystal on silicon
(LCOS)).|
|
Display driving modes
[
edit
]
Driving modes (activation of picture elements)
|
voltage driving
activation of pixels by voltage (e.g. LCD field effects). If the current is low enough this mode may be the basis for displays with very low power requirements (e.g. μW for LCDs without backlight).
|
current driving
activation of pixels by electric current (e.g. LED).
|
See also
[
edit
]
References
[
edit
]
- ^
Louis D. Silverstein, et al., Hybrid spatial-temporal color synthesis and its applications, JSID 14/1(2006), pp. 3?13
Further reading
[
edit
]
- Pochi Yeh, Claire Gu: "Optics of Liquid Crystal Displays", John Wiley & Sons 1999, 4.5. Conoscopy, pp. 139
|
---|
Enduring
| Plant-based
| |
---|
Other materials
| |
---|
|
---|
Impermanent
| |
---|
Carrier objects
| |
---|
Related topics
| |
---|