Input and Output devices part 1

Question 1

1.1 Screen types
LCD ~ name its advantages.(1)
operation - (2)

                                                                LCD = Liquid Crystal Display

Answer 1

Advantages:

• uses fluorescent backlight
• twisted crystals to block or allow light( not important)
  ~ cheap to manufacture

Question 2

1.1 Screen types

LCD - disadvantages(3)

Answer 2

Disadvantages:

~ heavier than LED, OLED
~ thicker than LED, OLED
~ lower resolution than OLED

Question 3

1.2 Screen types
LED ~ advantages(2)
operation - (2)

                                                        LED = Light Emitting Diodes

Answer 3

Advantages:

• uses LED backlight
• twisted crystals to block or allow light
• thinner than LCD
• cheaper to manufacture than OLED

Question 4

1.2 Screen types

LED - disadvantages(3)

Answer 4

Disadvantages:

~ thicker than OLED
~ lower resolution than OLED
~ more expensive to manufacture than LCD

Question 5

1.3 Screen types
OLED ~ advantages(2)
operation - (1)

                                                OLED = Organic Light Emitting Diodes

Answer 5

Advantages:

• each OLED pixel produces its own light
• thinnest of all screens
• highest resolution of all screens

Question 6

1.3 Screen types

OLED - disadvantages(1)

Answer 6

Disadvantages:

~ Most expensive to manufacture

Question 7

2.1 Touch screens
Capacitive ~ advantages (2)
operation - (2)

Answer 7

Advantages:

~ durable
~ supports multi-touch
- uses an electric current
- conductivity to the human body

Question 8

2.1 Touch screens

Capacitive ~ disadvantages(2)

Answer 8

~ expensive to manufacture

~ can’t be used with gloves

Question 9

2.2 Touch screens
Resistive ~ advantages(1)
operation - (2)

Answer 9

Advantages:

~ cheap to manufacture

• two layers of material
• detects where the layers have touched

Question 10

2.2 Touch screens

Resistive ~ disadvantages(3)

Answer 10

Disadvantages:

~ less durable
~ less multi-Touch support
~ less accuracy

Question 11

2.2.1 Touch screens
Infrared (thermal + optical) ~ advantages (0)
operation ( optical )- (2)

Answer 11

Advantages:

~ ( silence )

• lines across screen both ways
• detects where lines were broken

Question 12

2.2.2 Touch screens
Infrared ( thermal + optical ) ~ disadvantages (2)
operation (thermal) - (1)

Answer 12

Disadvantages:

~ expensive to manufacture
~ grid not useable on flat surface
- detects heat from human hand

Question 13

3.1 Scanners

2D scanners operation - (5)

Answer 13

Operation:

• the document is placed in the scanner which then emits a bright light ( usually a xenon lamp )
• a scam head scans the document making it an Image. The image is then sent to a lens which then focuses on the image.
• The image then is sent to a Charged Couple Device ( CCD ).
• The CCD produces electrical charges when light falls on it.
• the image can now be turned into a electronic form.

Question 14

3.2 Scanners

3D scanners - operation (1)

Answer 14

Operation:

-3D scanners use tomography by taking multiple pictures of the object from different angles and then piece them together to make 3D electrical object.

Question 15

4. Barcode scanners

Operation - (4)

Answer 15

Operation:

• barcode is read by a red laser ( LED )
• the white bars reflect the light and the black absorbs it.
• this reflected light is read by photoelectric cells.
• a pattern is generated and is converted to digital data eg, BWBBWBWB -> 10110101