# Output Devices
### 1. What an output device is

- A device that **takes processed data from the computer and presents it to the user** in a form they can perceive (visual, audio, tactile, physical).

### 2. Categories

- **Visual:** monitors, projectors, printers, plotters, VR / AR headsets.
- **Audio:** speakers, headphones, earbuds.
- **Physical:** printers, 3D printers, plotters, robotic arms.
- **Haptic / tactile:** vibration motors, force-feedback controllers, braille displays.

### 3. Monitors / displays

- The **main visual output** of a computer.
- **Technologies:**
    - **LCD** – common, backlit liquid crystals.
    - **LED** – LCD with LED backlight (today the standard term).
    - **OLED** – each pixel emits its own light, deeper blacks, used in premium phones and TVs.
    - **CRT** – old tube monitors, obsolete.
    - **E-ink** – low power, used in Kindle e-readers.
- **Parameters:** resolution (Full HD, 4K, 8K), refresh rate (60 / 144 / 240 Hz), response time, panel type (IPS, VA, TN), aspect ratio (16:9, 21:9).
- **Connections:** HDMI, DisplayPort, USB-C, DVI, VGA.

### 4. Projectors

- Display the image on a wall or projection screen.
- Used in classrooms, offices, home cinemas.
- **DLP, LCD, LCoS, laser** technologies.

### 5. Printers

- Produce **physical (hard) copies** of digital data.
- **Inkjet** – good for colour photos, cheaper printer but more expensive ink.
- **Laser** – fast, sharp text, cheaper per page; mono and colour versions.
- **Thermal** – receipts (no ink, heat-sensitive paper).
- **Dot matrix** – very old, still used for carbon copies (invoices).
- **3D printers** – build physical objects layer by layer (FDM, SLA).
- **Plotters** – draw large precise drawings (architecture, engineering).
- **Multifunction devices (MFP)** – print, scan, copy, fax.

### 6. Speakers & headphones

- Convert **electrical signal back into sound**.
- **Speakers:** stereo, 2.1, 5.1, 7.1 surround, soundbars, smart speakers (Alexa, Google Home).
- **Headphones / earphones / earbuds** – wired (3.5 mm jack, USB-C) or wireless (Bluetooth).
- **Active Noise Cancellation (ANC)** – AirPods Pro, Sony WH-1000XM.

### 7. VR / AR / MR devices

- **VR (Virtual Reality)** – fully replaces vision with virtual world (Meta Quest, Valve Index, Vision Pro).
- **AR (Augmented Reality)** – overlays digital content onto the real world (Apple Vision Pro, smartphone AR).
- Used in **gaming, training, education, medicine, design**.

### 8. Haptic / tactile feedback

- **Vibration motors** in phones and controllers.
- **Force feedback** in steering wheels and joysticks.
- **Braille displays** – output for visually impaired users.

### 9. Other physical output

- **Robotic actuators** – motors, servos, hydraulic / pneumatic systems in robotics and industry.
- **Smart-home actuators** – smart locks, thermostats, smart blinds.

### 10. Devices that are both input and output (I/O)

- **Touchscreens** – display + touch input.
- **Multifunction printers** – scan (input) + print (output).
- **Headset with microphone.**
- **VR headsets** – screen + motion tracking + audio.

### 11. Useful vocabulary

- Display, screen, resolution, pixel, frame rate.
- High-resolution, HD / Full HD / 4K / 8K.
- Print quality (DPI – dots per inch), toner, cartridge.
- Surround sound, stereo, mono, headset, mute.
- Glare, brightness, contrast, colour gamut.

### 12. Speaking strategy

Start with the definition: output = computer → user. List categories with examples. Cover monitors (most important) in detail, then printers, then audio (speakers / headphones). Mention VR / AR as modern and 3D printers as an exciting form of physical output.