User:Panjasan/Electronic Visual Displays
Electronic Visual Displays
A display device is an output device for presentation of information for visual or tactile reception, acquired, stored, or transmitted in various forms. When the input information is supplied as an electrical signal, the display is called electronic display. Electronic displays are available for presentation of visual and tactile information.
Tactile electronic displays are usually intended for the blind or visually impaired. They use electro-mechanical actuators to dynamically update a tactile image (usually of text) so that the image may be felt by the fingers (refreshable Braille display).
Common applications for electronic visual displays used to be television sets or computer monitors, but these days electronic visual displays tend to be ubiquitous as interface for large amounts of visual information.
Electronic Visual Displays - Classification
Electronic visual displays generate visual information according to the electrical input signal (analog or digital) either by generation of light (then they are called active displays) or, alternatively, by modulation of available light during the process of reflection or transmission (light modulators are called passive displays).
|Electronic Visual Displays|
|Active Displays||Passive Displays|
|visual information is provided by generation of light.||visual information is provided by modulation of light.|
|Effect||LCD + backlight (this combination is considered to be an active display)||LCD (liquid crystal display)|
|Example||LCD TV screen, LCD computer monitor||LCD watch (reflective)
see LCD classification
also see Electronic_paper
|Example||cathode ray tube (CRT)
field emission display (FED)
vacuum fluorescence display (VFD)
surface conduction electron emitter display (SED)
|Research & Manufacturing:
eInk Electronic Paper Displays
SiPix Microcup Electronic Paper
|Example||(thin or thick film) electro-luminescence (EL)
(inorganic or organic) light emitting diode (LED, OLED)
gas discharge display (Nixie tube)
|Research & Manufacturing:
ntera NanoChromics™ Technology
|Example||plasma display panel (PDP)||Research & Manufacturing:
|Example||Numitron, a 7-segment numerical display tube Numitron website||flap display
digital micromirror device (DMD)
interferometric modulation device (IMOD)
telescopic pixel display
Display Mode of Observation
Electronic visual displays can be observed directly (direct view display) or the displayed information can be projected to a screen (transmissive or reflective screen).
|Display Modes of Observation|
|direct view display||projection display|
|transmissive mode of operation||front-projection (with reflective screen)
e.g. video projector
|reflective mode of operation||rear-projection (with transmissive screen)
e.g. rear projection television screen
|transflective mode of operation||retinal projection (with or without combiner)
e.g. head mounted display
Layout of Picture Elements
Depending on the shape and on the arrangement of the picture elements of a display either fixed information ca be displayed (symbols, signs), simple numerals (7-segment layout) or arbitrary shapes can be generated (dot-matrix displays).
|Layout of Picture Elements|
characters, numbers and symbols of fixed shape (may be multiplexed addressed).
The following layouts are well known:
seven segment layout
fourteen segment layout
sixteen segment layout.
sub-pixels are arranged in a regular 2-dimensional array
(multiplex addressing required). Arbitrary shapes can be generated and displayed.
Generation and Control of Colors
Colors can be generated by selective emission, by selective absorption, transmission or by selective reflection.
|Color Generation and Control|
primary colors add up to produce white light
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
|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.
pentile arrangement, e.g. RGB+White
Each sub-pixel of a display devices must be selected (addressed) in order to be energized in a controlled way.
|Addressing Modes (selection of picture elements)|
each individual picture element has electrical connections to the driving electronics.
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.
|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 used in transmissive mode of operation (high transmittance required) or a non-transparent active matrix can be used for reflective LCDs (e.g. LCOS: liquid crystal on silicon).||
Display Driving Modes
|Driving Modes (activation of picture elements)|
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).
activation of pixels by electrical current (e.g. LED).
- Louis D. Silverstein, et al., Hybrid spatial-temporal color synthesis and its applications, JSID 14/1(2006), pp. 3-13
- SID - Society for Information Display International Conference Proceedings 1970 - 2008
- Journal of the Society for Information Display (JSID)
- Display-Metrology & Systems: Publications
- ISO 13406-2
- Pochi Yeh, Claire Gu: "Optics of Liquid Crystal Displays", John Wiley & Sons 1999, 4.5. Conoscopy, pp. 139