Input, Output, and Sensors Flashcards
output device
piece of hardware used to communicate the result of processed data
examples of output devices
printers, cutters, actuator, monitors, speakers, projectors, and headphone
printers
create (hard) copies of documents and images
Inkjet printers
use ink cartridges to spray tiny droplets of ink at any paper to form an image
Laser printers
uses a laser to apply a static charge to areas on the paper. Toner (a powdered ink) is then attracted to the static charge and sticks to the paper, forming an image
3D printer
used in computer aided design to produce solid objects of various materials. Design is made using CAD
When the printer runs out of paper
a signal called an interrupt is sent to the processor to request that the problem is dealt with
Projector
Used to display images and videos on large areas. Useful when output needs to be viewed by many people
LCD projectors (Liquid Crystal Display)
Creates an image by projecting light in three colors (RGB). Older technology.
DLP projectors (Digital light processing)
Uses thousands of tiny mirrors to reflect a digital image. Comp -> screen. Smaller, more portable, lesser quality images
LCD (Liquid Crystal Display)
Sandwich crystals between two sheets of glass. White backlight illuminates screen from behind. When crystals are solid, light cannot pass through. When an electrical current is applied to the crystals, light passes through, and an image is formed.
LED (Light emitting diode)
LEDs use light emitting diodes to generate light. Better contrast.
Have a better image quality, use less power, more cost effective, initial cost is higher
Speaker
Produce output inform of sound. Converts electrical signal into vibrations
Actuator
Takes a digital signal and outputs it as a physical movement
Cutters
Cut through materials such as glass
Coordinates are used to recognize the object
input devices
Used to input data into a computer for processing
examples of input device
keyboard, mouse, microphone
Keyboard (text)
Connected to a computer via USB/wireless
Each character has an ASCII value.
Each character pressed is converted to a digital signal
Each ASCII value has a binary value
The binary can be processed by the CPU to action the key press
Slow method of data entry, prone to errors
mouse (movement)
Mechanical ball, connected through USB port.
Microphone (sound)
Sound reaches the microphone’s diaphragma, which is attached to an electromagnetic apparatus which senses the vibrations and produces an electric current.
Touch Screen (movement, touch)
Useful when a user must select from a small range of options
Resistive touch screen
Top layer is flexible plastic with conductive film
The second layer is hard, with film.
Spacers keep them from touching.
When the screen is touched, both layers touch.
Measuring resistance on both points, a measurement of the position is found
Completes electrical circuit.
+: Cheap to manufacture
-: Not durable, poor visibility in the sun, less accuracy.
Capacitive touch screen
Transparent layer over screen, which is sensitive to the static electrical charge in human bodies.
When finger touches screen, current changes.
Change is detected and location can be detected. Point is sent back to controller.
+: Good visibility in the sun, durable, allows multitouch.
-: Glass screen can break, cannot be used with gloves.
infrared touch screen
Creates a grid of infrared light over screen, transmitted using LEDs.
When the user touches the screen, light beams are broken.
This information can be used to detect the location of touch.
+: Can be touched with gloved finger and stylus pen, durability is good, allows multitouch.
-: Expensive to manufacture, sensitive to dirt/dust, screen will shatter on impact.
Digital Camera: Images
Controlled by the microprocessor, which automatically adjusts shutter speed, focus, flash, etc.
Light passes through the lens onto a light sensitive cell made of pixels.
+: Images can be viewed immediately and can be edited easily on a computer.
-: Poor lens quality, limited memory for photo storage.
QR Code scanner
Quick Response code: Consists of a square black and white pattern, representing binary.
It is captured by a camera/scanner that breaks it down into a grid.
Processed light is reflected.
Black reflects less than white
Squares are decoded.
+: Holds a lot of data, doesn’t need a connected database, can store a variety of info (URL, payments)
-: Not suitable for info that changes regularly, needs a device/software that can read it.
Bar code scanner
A laser is shone at barcode; light is reflected to see if black or white.
Reflected light is read by sensor, pattern is converted into digital.
Used in categorizing and retrieval of store products.
Used in airports to track luggage.
+: Accurate and precise, reduces pricing error, improved customer service.
-: Possible misreads, barcodes need to be printed on labels and tags.
2D Scanner: Images and text
Documents are placed on the glass.
Scan head moves across so image can be sent to a lens.
Lens deconstructs light.
CCD produces electrical charges.
Digital image is produced by software.
Used to create 2D images.
Used to read passports.
+: Very accurate, high quality, large variety, higher resolution compared to digital camera.
-: Uses a lot of computer’s storage, can lose some of its quality.
3D Scanner: 3D objects
Scans objects using lasers to measure dimensions (h,w,l).
Laser detects details about shape and converts it into digital data.
+: Can scan tough surfaces, high resolution, and accuracy, less sensitive to changing light.
-: Shiny/transparent surfaces do not work.
Interactive whiteboard: Pressure
Allows users to write on the surface using a pen.
Text and drawings are then captured electronically and stored for later use.
+: Easy to use, can access files to display.
-: Expensive to install and maintain.
sensor
specific type of input device used to gather information about physical environment
types of sensor
- motion/infrared
- pressure
- light
- pH
- gas
- humidity
- sound
answer for sensors question
Sensor sends data readings to the microprocessor at set intervals.
To be understood, this data might need to be converted using an ADC (analogue to digital converter).
The microprocessor compares data readings against pre-set values it has stores (using a control program).
The microprocessor then makes a decision as to whether any action is needed.
If needed, the microprocessor will send a signal to instruct an output device to do something.
This may involve an actuator.
This process repeats in a continuous loop.
acoustic sensor
An acoustic sensor detects sound. This might include sound that is too low-pitched, too high-pitched or too quiet for humans to hear. One application of an acoustic sensor would be a burglar alarm, which could be used to detect a break-in.
accelerometer sensor
An accelerometer measures acceleration force (the rate of change of velocity). They are often used in smart phones to detect movement (for example, when a game is controlled by moving the phone itself).
flow sensor
Flow sensors measure the flow speed of liquids or gases in pipes. This is important in many situations. For example, a reduced flow speed in a pipe might mean there is a leak or a blockage in the pipe, and a flow sensor can be used to detect this situation.
gas sensor
Gas sensors can detect the presence of different gases. This is essential in many safety systems. For example, a gas sensor may be used to detect the presence of toxic gases in a chemical manufacturing plant.
humidity sensor
A humidity sensor detects water vapour in the air. Humidity sensors can be used in air conditioning or environmental control systems. For example, a greenhouse might use a humidity sensor to help a computer determine if the environment is correct for the plants growing there.
infra red sensor
An infra-red (IR) sensor is a type of light sensor that detects invisible infra-red light. Infra-red sensors are often used to measure the presence of objects. For example, an automatic door system might use an infra-red sensor to detect a person walking in front of the door.
level sensor
A level sensor uses a gyroscope to measure angular movement. This enables the sensor to detect if it is being tilted or rotated. A common application for these sensors is in smart phones, which can be controlled by tilting or waving the device.
light sensor
Light sensors detect light levels. This light could be visible light or invisible light, such as infra-red. Light sensors can be used in automatic lighting systems to switch on lights when natural light levels fall below a certain level.
magnetic field sensor
A magnetic field sensor measures the strength of a magnetic field. They are sometimes used in geophysical surveys.
moisture sensor
A moisture sensors measures the presence of water.
pH sensor
A pH sensor detects how acidic or alkaline a substance is. pH sensors might be used in swimming pools or aquariums to check the pH of the water, or in a chemical factory to help ensure the pH level is correct.
pressure sensor
A pressure sensor may refer to two different types of sensor:
A sensor which measures the pressure of a liquid or gas, such as in a pipe.
A sensor which means the weight pushing down on it, such as a floor plate which can detect the pressure of a person standing on it.
proximity sensor
A proximity sensor can detect when an object is close, even if the objects are not touching. They are used in many situations where collisions need to be avoided. For example, many cars have proximity sensors to warn the driver when an object is very close to the front or rear of the car.
temperature sensor
Temperature sensors measure heat energy. Many home appliances such as microwaves, kettles and washing machines contain temperature sensors. This helps ensure they are working correctly and safely.
