An output device is any hardware that receives processed data from the CPU
and presents it in a form that humans or other systems can use.Output Device = Hardware that converts digital signals from the CPU into
a usable form (visual, audio, or physical).
2. Categories of Output Devices#
3. Visual Output Devices#
🖥️ Monitor (Screen / Display)#
The most common output device — displays text, images, and video.| Type | Full Name | How it Works | Key Feature |
|---|
| LCD | Liquid Crystal Display | Liquid crystals block/allow backlight through | Thin, low power |
| LED | Light Emitting Diode | LEDs act as backlight for LCD panel | Brighter, more energy efficient |
| TFT | Thin Film Transistor | A type of LCD with a transistor per pixel | Sharper image, faster refresh |
| OLED | Organic LED | Each pixel produces its own light | Deep blacks, no backlight needed |
Resolution — number of pixels (e.g., 1920 × 1080); higher = sharper image.
Refresh rate — how many times per second the image updates (Hz).
Screen size — measured diagonally in inches.
📽️ Projector#
Projects an image from a computer onto a large external surface (screen or wall).
Useful when the image needs to be seen by a large audience.
Resolution and brightness (measured in lumens) are key specifications.
4. Printed Output Devices#
Used in: Prototyping, medical implants, prosthetics, manufacturing, architecture models.| ✅ Advantages | ❌ Disadvantages |
|---|
| Creates complex 3D shapes | Very slow |
| Produces prototypes cheaply | Materials can be expensive |
| Customisable for each print | Lower strength than manufactured parts |
5. Audio Output Devices#
🔊 Speakers#
Convert digital audio signals from the computer into sound waves.
The CPU sends a digital signal → converted to analogue by a DAC (Digital-to-Analogue Converter) → drives the speaker cone → produces sound.
🎧 Headphones#
Work on the same principle as speakers but are worn directly on or in the ears.
Provide personal audio output without disturbing others.
6. Control Output Devices (Actuators)#
An actuator is an output device that causes a physical action or movement in the real world. Commonly used in embedded systems and automated control.| Actuator Type | What it Does | Example Use |
|---|
| Electric Motor | Produces rotation or movement | Washing machine drum, robotic arm |
| Heater | Generates heat | Central heating system, oven |
| Buzzer / Alarm | Produces an audio alert | Burglar alarm, fire alarm |
| Light / LED | Emits light as a signal | Traffic lights, indicator lamps |
| Valve / Pump | Controls flow of liquid or gas | Irrigation system, fuel injection |
Note: Actuators are the output side of embedded/control systems —
they are the equivalent of sensors on the input side.
7. Choosing the Right Output Device#
| Scenario | Best Output Device | Reason |
|---|
| Printing high-quality colour photos | Inkjet Printer | Best colour reproduction |
| Printing 500 black & white reports | Laser Printer | Fast, cheap per page |
| Printing duplicate invoices | Dot Matrix Printer | Can create carbon copies |
| Displaying a presentation to 100 people | Projector | Large image for audience |
| Producing a precise CAD engineering plan | Plotter | High accuracy vector output |
| Creating a physical prototype | 3D Printer | Produces physical 3D objects |
| Playing audio from a computer | Speakers | Converts digital signal to sound |
| Controlling a motor in an embedded system | Actuator (Motor) | Produces physical movement |
8. Comparison of Printer Types#
| Feature | Inkjet | Laser | Dot Matrix |
|---|
| Print quality | High (colour) | High (text) | Low |
| Print speed | Slow | Fast | Very slow |
| Cost to buy | Low | High | Medium |
| Cost per page | High | Low | Very low |
| Noise level | Quiet | Quiet | Very noisy |
| Carbon copies? | ❌ No | ❌ No | ✅ Yes |
| Best for | Photos, home use | Office documents | Receipts, forms |
9. Key Vocabulary#
| Term | Definition |
|---|
| Output Device | Hardware that presents processed data from the CPU |
| Resolution | Number of pixels on a screen; higher = sharper image |
| Inkjet Printer | Sprays liquid ink droplets onto paper |
| Laser Printer | Uses laser + toner powder fused by heat onto paper |
| Dot Matrix Printer | Impact printer using pins and ink ribbon; prints carbon copies |
| Plotter | Draws precise lines using a moving pen; used for CAD |
| 3D Printer | Builds physical 3D objects layer by layer |
| Actuator | An output device that causes physical movement or action |
| DAC | Digital-to-Analogue Converter — converts digital signals to analogue |
| Toner | Dry powder used in laser printers |
10. Exam Tips ✅#
Always justify your choice of output device — name it and explain why it suits the scenario.
The dot matrix printer is the only printer that can produce carbon/duplicate copies — this is its main exam use case.
Know that speakers/actuators use a DAC (Digital-to-Analogue Converter) —
the opposite of sensors which use an ADC.
Plotters are for technical/precise drawings (CAD), not general documents.
3D printers produce physical objects — always link them to prototyping or manufacturing.
A touch screen is both input and output — the screen is an output device.
For actuators, link them back to embedded systems and control systems.
Cambridge (CIE) IGCSE Computer Science — 0478 / 0984 Modified at 2026-04-03 09:53:31
