Computer Hardware Chapter 3: Input Devices

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is a barcode?

A series of dark and light parallel lines of varying thickness that represent numbers.

Which of the following best describes how barcode scanners read barcodes?

By scanning in one direction only

By using a blue laser

By generating a sound for each digit

By reflecting light off the barcode (correct)

The digit on the left side of the barcode always begins with a dark bar.

False

What does QR stand for?

Quick Response Signup and view all the answers

Which of the following are advantages of using barcodes for management?

Reduced need to price every stock item Signup and view all the answers

What is one of the main disadvantages of QR codes compared to traditional barcodes?

They can transmit malicious code Signup and view all the answers

Each digit in a barcode is represented by bars of _ to _ blocks thick.

1 to 4 Signup and view all the answers

What happens to the stock item record when a barcode is scanned?

The barcode number is looked up, and the stock item record is updated. Signup and view all the answers

Match the following input/output devices with their usage:

Keypad = To key in numbers and weights Screen/Monitor = To show the cost of an item Speaker = To make beeping sounds Printer = To print out receipt Signup and view all the answers

What is one advantage of using QR codes rather than traditional barcodes?

QR codes can store more information than traditional barcodes. Signup and view all the answers

How many bytes of data can be stored on a QR code that contains 40 × 40 tiny squares?

1600 bytes Signup and view all the answers

What is the purpose of the three large squares at the corners of a QR code?

They help the scanner determine the orientation of the QR code. Signup and view all the answers

What is one disadvantage of using QR codes?

They require a camera or scanning device to read. Signup and view all the answers

What happens when a photograph is taken with a digital camera?

Light passes through the lens onto a light-sensitive cell made up of millions of tiny sensors. Signup and view all the answers

What does an 8-bit ADC give in terms of brightness levels per pixel?

256 possible brightness levels. Signup and view all the answers

What RGB system do most cameras use to measure color?

24-bit RGB system. Signup and view all the answers

What is the common method of data entry on computers?

Keyboards. Signup and view all the answers

What are ergonomic keyboards designed to do?

Reduce the risk of repetitive strain injury. Signup and view all the answers

How does a microphone convert sound waves into electrical signals?

Through a diaphragm vibrating in response to sound waves. Signup and view all the answers

What technology allows multi-touch facilities?

Infrared touch screens Signup and view all the answers

What component in an optical mouse generates electric pulses from reflected light?

CMOS. Signup and view all the answers

How does the computer determine the coordinates of the mouse movement?

By analyzing the changing image patterns from the optical mouse. Signup and view all the answers

What material makes up the upper layer of resistive touch screens?

Flexible polyethylene Signup and view all the answers

Which of the following is a disadvantage of infrared touch screens?

Sensitive to water or moisture Signup and view all the answers

Resistive touch screens support multi-touch facilities.

False Signup and view all the answers

What is one advantage of resistive touch screens?

Good resistance to dust and water Signup and view all the answers

What happens when the two layers of a resistive touch screen are touched?

They make contact and complete a circuit which changes the voltage. Signup and view all the answers

Which of the following materials is used for the bottom layer of resistive touch screens?

Glass Signup and view all the answers

What is a potential issue with resistive touch screens in strong sunlight?

Poor visibility Signup and view all the answers

What is a benefit of using an optical mouse over a mechanical mouse?

No moving parts Signup and view all the answers

Optical mice typically use USB wired connections.

False Signup and view all the answers

Which type of scanner is commonly used to input hard copy documents?

Optical Scanner Signup and view all the answers

What does a charge-coupled device (CCD) do in a scanner?

Converts light into an electric current Signup and view all the answers

A ___ scanner produces a three-dimensional image of solid objects.

3D Signup and view all the answers

What does OCR stand for?

Optical Character Recognition Signup and view all the answers

Capacitive touch screens can only detect touches from bare fingers.

True Signup and view all the answers

What is a common type of technology used in touch screens?

Capacitive Signup and view all the answers

Match the type of scanner with its application:

2D Scanner = Reading passports at airports 3D Scanner = Creating models for CAD CT Scanner = Medical imaging MRI Scanner = Soft tissue imaging Signup and view all the answers

What is one advantage of projective capacitive touch screens over resistive touch screens?

Multi-touch capability Signup and view all the answers

Infrared touch screens use a glass screen with an array of ___ and infrared transmitters.

sensors Signup and view all the answers

Study Notes

Input and Output Devices: Barcodes and QR Codes

Barcodes consist of dark and light parallel lines, each digit (0-9) represented by unique patterns.
Digits on the left have odd numbers of dark elements; those on the right have even numbers.
Scanning process: Red laser or LED illuminates barcode; dark areas reflect little light, allowing for digit recognition.
The scanned barcode converts to digital data, creating a pattern for interpretations, e.g., ‘3’ as L D D D D L D (binary: 0111101).
Barcodes enhance checkout efficiency in supermarkets with various input/output devices, including:
- Keypad: Input for item quantities or weights.
- Screen/Monitor: Displays item cost and information.
- Speaker: Provides audible feedback on barcode reads.
- Printer: Generates receipts/itemized lists.
- Card Reader: Reads credit/debit cards using PIN or contactless methods.
- Touchscreen: Allows item selection for loose produce.

Barcode Operations

After scanning, the barcode number is matched in the stock database, identifying the item.
Stock information, including price and details, is retrieved and updated after each scan, ensuring inventory control.
Automatic re-ordering occurs when stock levels are below a specified threshold.

Advantages of Barcodes

Streamlines price changes and provides real-time sales data.
Reduces manual pricing efforts, enhancing operational efficiency.
Allows tracking of customer purchasing patterns via loyalty cards.

Customer Benefits of Barcodes

Expedites checkout processes and minimizes pricing errors.
Provides itemized billing, leading to transparency in transactions.
Enhances management of product freshness and sell-by dates.

QR Codes: An Advanced Barcode

QR codes contain a matrix of dark and light squares, significantly holding more data (up to 4296 characters).
QR codes feature alignment squares for scanning accuracy and consistency.
Readable via smartphone cameras, facilitating widespread applications such as advertising and boarding passes.

Advantages of QR Codes

Greater information storage capacity compared to traditional barcodes.
Built-in error-checking systems minimize scanning errors.
Easier and less expensive to read, relying on smartphone camera capabilities.

Disadvantages of QR Codes

Various formats can lead to compatibility issues.
Potential security risks, such as malicious code embedding.

New Developments

Introduction of frame QR codes allows branding integration with graphics and images, enhancing marketing potential.### Digital Cameras
Modern digital cameras connect to computers via USB or Bluetooth for file transfer.
Controlled by embedded systems for automatic functions such as shutter speed, focus, flash, aperture size, image size adjustment, and red-eye removal.
Photographic image capture occurs when light hits a light-sensitive cell made up of tiny sensors as photodiodes (CCD).
Each sensor is a pixel, converting light into electric charges, forming a digital image array using an analogue to digital converter (ADC).
An 8-bit ADC provides 256 brightness levels per pixel, while most cameras use a 24-bit RGB system for color value representation ranging from 0 to 255.
Pixel values can form binary patterns, e.g., RGB colors like orange quantified as red=215, green=165, blue=40.
Image quality depends on camera lens, sensor quality, pixel count, lighting levels, and storage format (e.g., JPEG, raw).
Smartphones now match digital cameras in pixel count but often have inferior lens quality and memory limitations.

Keyboards

Keyboards are the most common data entry method for computers, tablets, and mobile phones.
They connect via USB or wirelessly, with many tablets and phones utilizing virtual or touch screen keyboards.
Each keypress generates a digital signal corresponding to an ASCII value, interpreted by the computer's CPU.
Keyboards are relatively slow and prone to errors but provide ease of text entry.
Frequent use can lead to repetitive strain injury (RSI); ergonomic keyboards are designed to help alleviate this.

Microphones

Microphones convert sound waves into electric currents, either built-in or external via USB or Bluetooth.
Sound waves cause a diaphragm to vibrate, creating movement in a coil wrapped around it, generating an electric current.
The output is usually analogue, subsequently converted to a digital signal by the computer's sound card for processing or storage.

Optical Mice

Optical mice utilize tiny cameras to capture 1500 images per second, functioning on various surfaces.
A red LED light reflects off surfaces, picked up by a CMOS that generates electric pulses sent to a digital signal processor (DSP) for cursor movement.
Benefits include reliability due to lack of moving parts and cleanliness from potential dirt accumulation.

Scanners

Scanners come in two-dimensional (2D) and three-dimensional (3D) types; 2D scanners are most common for digitizing hard copy documents.
Scanning involves raising the cover, placing the document, and closing it to illuminate the document with a xenon lamp or LED.
A scan head moves across the document; the focused image hits a CCD, converting light into electric current.
The scanned image becomes an electronic form, with software converting it into a digital image.
Optical character recognition (OCR) software can convert scanned text into editable file formats.### Scanning Technologies
Scanned images can be edited by importing into a word processor; if a photograph, the output is a JPEG image.
3D scanners create digital representations of solid objects using x, y, and z coordinates by capturing images at various points.
Scanned 3D images are utilized in computer-aided design (CAD) and 3D printing, allowing physical models to be produced.
Various technologies for 3D scanning include lasers, magnetic resonance, and white light.

Application of 2D Scanners

Airports utilize 2D scanners for passport reading, employing Optical Character Recognition (OCR) technology to create digital images of passport pages.
OCR software can extract text and populate it into databases, potentially storing it in ASCII format.
2D images from passports and live photographs of passengers are compared using facial recognition software to verify identities.
Key facial features compared include distance between the eyes, nose width, cheekbone shape, jaw length, and eyebrow shape.

Computed Tomographic (CT) Scanners

CT scanners generate 3D images of solid objects through a method called tomography, which involves taking thin "slices" of images.
Each slice is typically created using X-rays, radio frequencies, or gamma imaging.
CT scanners are known for producing detailed images through a combination of numerous 2D slices.

Touch Screen Technologies

Touch screens allow users to interact through touch, similar to a mouse, and are prevalent in devices like mobile phones and tablets.
Common types of touch screen technologies include capacitive, infrared, and resistive screens.

Capacitive Touch Screens

Capacitive screens consist of a protective glass layer, conductive layer, and glass substrate, responding to changes in the electrostatic field when touched.
They work with bare fingers or specialized styluses, with two types: surface capacitive and projective capacitive screens.
Projective capacitive screens enable multi-touch capability and are more resistant to scratches and sunlight compared to surface capacitive screens.

Infrared Touch Screens

Infrared touch screens use sensors and infrared transmitters arranged in a matrix; breaking the beams indicates touch.
They allow multi-touch features and maintain functionality despite minor screen damage.
Sensitivity to water and inadvertent activation are notable disadvantages.

Resistive Touch Screens

Comprised of two layers of resistive material, these screens detect touch through contact that completes an electrical circuit.
They offer good durability against dust and water and can be used with fingers, styluses, and while wearing gloves.
Disadvantages include lower sensitivity requiring firmer presses, lack of multi-touch support, and poor visibility in bright conditions.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the fundamentals of input and output devices in computer hardware with a focus on barcode scanners. This quiz delves into how barcodes work and their applications in technology. Test your knowledge on various input methods and their significance.