A liquid crystal display (LCD) (液晶ディスプレイ) is a device that shows images by having liquid crystal (液晶) pass or block light shining from behind.
The backlight gives off white light
Liquid crystal adjusts how much light passes
Color filters add color
The image appears on the screen
The light, dark and color of every dot combine into one image.
4 / 4
Liquid crystal does not glow by itself, so a backlight (バックライト) sits at the back of the screen and voltage changes how its light passes at each dot to make light and dark. An image is a collection of pixels (画素, tiny dots that show color), and the number of pixels in width × height is called the screen's resolution (解像度).
AnalogyIt works like window blinds. Just as tilting the slats lets outside light in or shuts it out to change how bright a room is, the screen makes light and dark the same way.
How to rememberLiquid crystal is a substance that flows like a liquid yet lines up like a crystal. Picture it as a gatekeeper that turns to let light through or not.
Exam points
ExamIf you lower the resolution (解像度) without changing the screen size, fewer pixels make up the image and each one shows larger, so text and icons appear bigger.
ExamCommon width × height pixel combinations of screen resolution have standard names; VGA, for example, means 640×480.
An organic EL display (OLED) (有機ELディスプレイ) is a device that shows images using organic elements, one per pixel, that give off their own light when current flows.
Because each pixel glows on its own, no backlight is needed, and a pixel left unlit shows black as it is. Without a light source layer it is easier to make thin and light, and some products even have screens that bend.
AnalogyIt is like the lit windows of a building at night. Simply switching each room's light on or off makes a pattern appear on the building's face.
How to rememberEL stands for Electro Luminescence, light produced by electricity. The name itself tells you it makes its own light.
Liquid Crystal Display (LCD) vs. Organic EL Display (OLED)
Aspect
Liquid Crystal Display (LCD)
Organic EL Display (OLED)
Key differenceLight source
Liquid crystal adjusts light from a rear backlight
A head-mounted display (HMD) (ヘッドマウントディスプレイ) is a display device worn on the head that shows images on a small screen in front of the eyes.
Paired with sensors that detect which way the head faces, it switches the image to match the direction you look. It serves as a device for VR (仮想現実, virtual reality), which fills your view with images, and for AR (拡張現実, augmented reality), which lays information over the real scene.
AnalogyMuch as the view beyond a binocular's small lenses looks huge, a small screen placed right before the eyes fills most of your view and looks large.
How to rememberBreak the English apart: a display you mount on your head, and where it goes is plain to see.
A projector (プロジェクター) is a display device that enlarges an image with light and casts it onto a screen or wall.
It has no screen of its own; it enlarges the image made inside through a lens and projects it onto a distant surface. It suits meeting rooms and classrooms where many people watch the same image, and its brightness is rated in lumens (ルーメン), a measure of the amount of light.
AnalogyIt is like the game of casting big shadow shapes on a wall with a flashlight. Putting a picture into the light turns a blank wall into a screen.
How to rememberProject means to throw forward. Remember it by its roots: a device that throws light forward to show an image.
A printer (プリンター) is an output device that prints a computer's text and images onto paper or other flat surfaces.
Method
How it prints
Features
Inkjet
Sprays tiny ink droplets from nozzles onto paper
Compact, many home models, also used for photos
Laser
Toner powder sticks to a drum drawn on with light, moves to paper and is fixed by heat and pressure
Fast, suited to high-volume office printing
Impact
Print head pins strike the paper through an ink ribbon
With pressure-copy paper stacked, makes duplicates at the same time
Printing methods differ in speed, fineness and suitable uses, and the table shows how the main methods compare. Print speed is expressed in ppm (pages output per minute), and print fineness in dpi (dots per inch).
AnalogyInkjet is like spraying colored droplets with a mister, laser is like laying colored powder on paper and pressing it in with an iron, and impact is like stamping hard enough to mark the sheet underneath too.
How to rememberImpact means a forceful blow. The striking force reaches the sheet underneath, which links it to the method that can make copies.
Exam points
ExamWith the impact method (インパクト方式), the printing pressure passes through the paper, so with copy paper stacked, one print also produces the duplicate.
ExamThe laser method (レーザー方式) moves powdered toner from a drum to paper and fixes it with heat, while the inkjet method (インクジェット方式) turns liquid ink into fine droplets that hit the paper directly.
Examppm expresses speed as pages per minute and dpi expresses fineness as dots per inch, and for both a larger value means higher performance.
A 3D printer (3Dプリンター) is an output device that builds a solid object by forming material into thin layers and stacking them, based on 3D shape data.
Prepare 3D shape data
Split the data into thin slices
Stack material layer by layer in each slice's shape
A solid object you can hold is made
Once every layer is stacked, the object matches the data.
4 / 4
It splits shape data made with tools such as 3D CAD (3次元CAD) into thin slices and builds the form by stacking material such as resin one layer at a time from the bottom. Without making a mold, it can produce prototypes or one-off parts in a short time.
AnalogyIt is like cutting cardboard along a map's contour lines and gluing the pieces on top of one another from the bottom to build a model mountain.
How to remember3D means width, depth and height. Tell it apart by the name: a paper printer with height added.
Exam points
ExamWhat you give a 3D printer (3Dプリンター) is 3D shape data, and what comes out is the solid object itself, ready to hold.