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利用者:加藤勝憲/電子画像表示装置

電子画像表示装置は、電子的に伝送される画像、映像、文字を表示できる表示装置である。

テレビジョンの表示部、コンピュータの文字・画像表示器電子看板などがある。タブレット・コンピューター、スマートフォン、情報家電のようなモバイル・コンピューティング・アプリケーションでは、どこにでもある。多くの電子ビジュアル・ディスプレイは、非公式にスクリーンと呼ばれている。

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.

2000年代初頭から、特にコンピューター用途でブラウン管(CRT)が廃止されたため、フラット・パネル・ディスプレイが業界を支配し始めた。2010年代半ばからは、曲面ディスプレイ・パネルがテレビ、コンピューター・モニター、スマートフォンに使われ始めた。

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.

種類[編集]

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[編集]

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).

Electronic visual displays
Active displays Passive displays
present visual information by emitting light present visual information by modulating light
Principle Liquid crystal display (LCD) + backlight

(this combination is considered an active display)
LCD
Example LCD TV screen, LCD computer monitor LCD watch (reflective)

see LCD classification
Principle Cathodoluminescence Electrophoresis

also see Electronic paper
Example Cathode ray tube (CRT)

Field emission display (FED)

Vacuum fluorescent display (VFD)

Surface-conduction electron-emitter display (SED)
Research & manufacturing:



Principle Electroluminescence Electrochromism
Example (thin or thick film) electro-luminescence (EL)

(inorganic or organic) light emitting diode (LED, OLED)



gas discharge display (Nixie tube)
Research & manufacturing:

Principle Photoluminescence Electrowetting
Example Plasma display panel (PDP) Research & manufacturing:

Principle Incandescence

Electromechanical modulation
Example Numitron, a 7-segment numerical display tube flap display

flip-disk display

digital micromirror device (DMD)

Interferometric modulator display (IMOD)

FTIR (unipixel)

Display mode of observation[編集]

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.

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

(e.g. transflective LCD)
retinal projection (with or without combiner)

e.g. head mounted display

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[編集]

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).

Layout of picture elements
Segmented displays

characters, numbers and symbols of fixed shape (may be multiplex addressed)

The following layouts are well known:

Seven-segment display

Fourteen-segment display

Sixteen-segment display
Dot-matrix displays

sub-pixels are arranged in a regular 2-dimensional array

(multiplex addressing required); arbitrary shapes can be formed and displayed

Emission and control of colors[編集]

Colors can be generated by selective emission, by selective absorption, transmission or by selective reflection.

Addressing modes[編集]

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[編集]

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).

関連項目[編集]

脚注・参考文献[編集]


関連文献[編集]

  • Pochi Yeh, Claire Gu: "Optics of Liquid Crystal Displays", John Wiley & Sons 1999, 4.5. Conoscopy, pp. 139

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