Transcript What is a Mouse?

Standard Input Methods
Standard Methods
of Input
This lecture includes the following sections:
 The Keyboard
 The Mouse
 Variants of the Mouse
 Devices for the Hand
Optical Input Devices
Audio-Video Input Devices
The Keyboard
• It is an input device.
• Its design came from typewriters that did not use
electricity.
• A person can type a document, access menus, play
games and perform variety of other tasks.
• Keys, called Keycaps are the same size and shape from
keyboard to keyboard.
• These are also placed at the similar distance from one
another in a similar pattern
The Keyboard - Standard Keyboard Layout
• A standard computer keyboard has about 100 keys.
• Most keyboards use the QWERTY layout, named for
the first six keys in the top row of letters.
The Keyboard - Standard Keyboard Layout
Most keyboards have keys arranged in five groups:
1. Alphanumeric keys
2.
Numeric keypad
3.
Function keys
4.
Modifier keys
5.
Cursor-movement keys
ACADEMIC RECORDS
Password
ENTER
* * * * *
Invalid Password
Variants of Keyboard
• Das Keyboard:
• Completely black keyboard with weighted keys
• These weighted keys require more pressure from a
person's strongest fingers and less pressure from the
weaker ones.
• True-touch Roll-up keyboard:
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Flexible and can be rolled up to fit in a backpack or bag.
Variants of Keyboard
• Illuminated keyboards:
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It uses light-emitting diodes or electroluminescent film
to send light through the keys or the spaces between keys.
• Optimus keyboard:
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It has organic light-emitting diodes (OLEDs) in the keys.
Users can change what letter, command or action each key
represents, and the OLED can change to display the new
information.
The Keyboard - How a Keyboard
Works
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A keyboard is a lot like a miniature computer.
It has its own processor and circuitry that carries information
to and from that processor.
A large part of this circuitry makes up the key matrix.
Key Matrix
Parts of Keyboard Circuitry
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Keyboard controller
Keyboard buffer
Scan code
Interrupt request
The Keyboard - How a Keyboard Works
When you press a key:
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The keyboard controller detects the keystroke.
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The controller places a scan code in the keyboard
buffer, indicating which key was pressed.
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The keyboard sends the computer an interrupt
request, telling the CPU to accept the keystroke.
How the Computer Accepts Input from
the Keyboard
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Keyboard controller
Keyboard buffer
Scan code
Interrupt request
Repeat rate
The Mouse
• What is a Mouse?
• Mouse Techniques
The Mouse - What is a Mouse?
•
The mouse is a pointing device. You use it to move
a graphical pointer on the screen.
•
The mouse can be used to issue commands, draw,
and perform other types of input tasks.
The Mouse - Mouse Techniques
Using the mouse involves five techniques:
1. Pointing; Move the mouse to move the on-screen pointer.
2. Clicking; Press and release the left mouse button
once.
3. Double-clicking; Press and release the left mouse
button twice.
4. Dragging; Hold down the left mouse button as you
move the pointer.
5. Right-clicking; Press and release the right mouse button.
Variants of the Mouse
• Trackballs
• Trackpads
• Integrated Pointed Devices
Variants of the Mouse - Trackballs
• A trackball is like a mouse turned upside-down.
• Use your thumb to move the exposed ball and your
fingers to press the buttons.
Many styles of
trackball are
available.
Variants of the Mouse - Trackpads
•
A trackpad is a touch-sensitive pad that provides the
same functionality as a mouse.
•
To use a trackpad, you glide your finger across its
surface.
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Trackpads provide a set of buttons that function like
mouse buttons.
Variants of the MouseIntegrated Pointing Devices
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An integrated pointing device is a small joystick built
into the keyboard.
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To use an integrated pointing device, you move the
joystick.
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These devices provide a set of buttons that function
like mouse buttons
Alternative Methods
Of Input
Input Devices for the Hand
• Pen, sometimes called
a stylus
• Touch screen
• Game controller
Devices for the Hand - Pens
•
With a pen-based system, you use an electronic pen
to write on the screen and choose commands.
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Pens are common input devices for handheld
computers, like “personal digital assistants (PDAs).”
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Pens are handy for making notes or selecting
commands, not for inputting a lot of text.
The user can point, tap,
draw and write on the
computer’s screen with a
pen.
Devices for the Hand - Touch Screens
• Touch-screen systems accept input directly through
the monitor.
• Touch screens use sensors to detect the touch of a
finger. They are useful where environmental
conditions prohibit the use of a keyboard or mouse.
• Touch-screen systems are useful for selecting options
from menus.
Devices for the Hand - Game Controllers
• The two primary types of game controllers are
joysticks and game pads.
• Game pads is a small, flat device that usually
provides two sets of controls one for each hand.
• Joysticks are popular for flight simulator and
driving games.
Optical Input Devices
• Bar code reader
• Image scanner and
optical character
recognition (OCR)
Optical Input Devices - Bar Code Readers
•
Bar code readers can read bar codes—patterns of
printed bars.
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The reader emits light, which reflects off the bar code
and into a detector in the reader. The detector
translates the code into numbers.
•
Flatbed bar code readers are commonly found in
supermarkets. Courier services often use handheld
readers.
Bar code readers
commonly track
sales in retail
stores
Optical Input Devices –
Image Scanners and OCR
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Image scanners digitize printed images for storage and
manipulation in a computer.
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A scanner shines light onto the image and interprets
the reflection.
•
Optical character recognition (OCR) software
translates scanned text into editable electronic
documents.
OCR
• The basic principle of a scanner is to analyze
an image and process it in some way.
• Image and text capture (optical character
recognition or OCR) allow you to save
information to a file on your computer.
• You can then alter or enhance the image,
print it out
Parts Of Scanner
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Charge-coupled device (CCD) array
Mirrors
Scan head
Glass plate
Lamp
Lens
Cover
Filters
Stepper motor
Stabilizer bar
Belt
Power supply
Interface ports)
Control circuitry
Working
• The core component of the scanner is the CCD array.
• CCD is the most common technology for image
capture in scanners.
• CCD is a collection of tiny light-sensitive diodes,
which convert photons (light) into electrons (electrical
charge). These diodes are called photosites.
• Each photosite is sensitive to light -- the brighter the
light that hits a single photosite, the greater the
electrical charge that will accumulate at that site.
Document
being
scanned
Converts
diode signals
to numbers
To computer
Light source, lens
and diode array
Types Of Scanner
• Flatbed scanners also called desktop scanners, are
the most versatile and commonly used scanners.
• Sheet-fed scanners are similar to flatbed scanners
except the document is moved and the scan head is
immobile. A sheet-fed scanner looks a lot like a small
portable printer.
• Handheld scanners use the same basic technology
as a flatbed scanner, but rely on the user to move
them . This type of scanner typically does not provide
good image quality. However, it can be useful for
quickly capturing text.
Audio-Visual (Multimedia) Input Devices
• Microphones and Speech Recognition
Software
• Video Input
• Digital Cameras
Audio-Visual (Multimedia) Input Devices Microphones and Speech Recognition
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Microphones can accept auditory input. A
microphone requires a sound card in the PC.
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A sound card can digitize analog sound signals, and
convert digital sound signals to analog form.
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With speech recognition software, you can use your
microphone to dictate text, navigate programs, and
choose commands.
Analog Sound Signals
Digital Audio Output
[electrical signals]
(ex. 11100011) to
computer
Analog Signals are Digitized
Audio-Visual (Multimedia) Input Devices –
Video Input
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PC video cameras digitize full-motion images.
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Digital cameras capture still images.
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These cameras break images into pixels and store
data about each pixel.
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Video images may be compressed to use less memory
and storage space.
Assignment # 2
• Discuss in detail optical Input Devices,
explain the working of them.
• Discuss in detail Audio-Video Input
Devices and their working.