investigating crt technology

7/23/2019 Investigating CRT Technology

1/19

1

1

Investigation CRT Technology: Using a

Magnetic Field to Measure Pixel Pitch

Anthony MollicaUBC Physics

Physics 4! Fe"ruary 11# !1!


2/19

$oals o% this la"

&vervie' o% CRT Technology

Calculation o% Theoretical (ertical Pixel Pitch )*x+

,lectro-agnetic Physics Theory

,x.eri-ental *x /eter-ination

Re%erences

0u--ary

Presentation &utline


3/19


4/19

CRT stands %or Cathode Ray Tu"e

Co-.onents o% a CRT T( ,lectron gun: 0.eeds u. electrons

Magnets: There are hori5ontal and vertical -agnets to de%lect the electrons

Phos.hor %ila-ents on the screen that the electrons hit

4

6o' /oes a CRT T( 2or78


5/19

,lectrons are -ove at 913 s.eed o% light

The interior o% the co-.uter screen is a

(acuu-

,lectrons are de%lected "y -agnetstargeting dots on the screen

inetic energy o% the electron trans%erred

to light energy

Red# "lue or green is created

;

ight ,-ission %ro- a CRT


6/19

Red# "lue and green are created %ro- the electron "ea-

Mixtures o% .ri-ary colours can create all colours

htt.:c"ug


7/19

Fro- distance the eye cannot see individual dots

3 dots )R#$#B+ cluster together and %or- a .ixel

Pixels can there%ore .roduce any colour

Many .ixels .roduce an i-age

@

2hy is the i-age continuous8

Pixel

/ot


8/19

3 .ri-ary colours loo7 li7e one colour

6o' the screen is re%reshed htt.:'''

E

6o' the CRT Fools the ,ye


9/19

/ot .itch is the diagonal distance "et'een dots o% the sa-e colour )/P+

(ertical dot .itch is vertical distance "et'een sa-e colour dots For this la" 'e are interested in (ertical /ot Pitch

2e 'ill call the Vertical Dot Pitch x for this lab

D

Calculation o% /ot Pitch Theoretical *x

/P)*x+)3+

?!

Got to 0cale

/P*x

*x


10/19

A re%erence value %or /ot Pitch )/P+ !


11/19

/irection o% /e%lected ,lectrons $iven "y Cross .roduct or Right 6and Rule )R6R+

11

6o' ,lectrons in a CRT are /e%lected

Path o% electron )vx+

/irection Force )F+

Magnetic Field )B+

Gegative Charge Fli.s %orce do'n'ards

since v# and B are .er.endicular


12/19

Magnetic Field around a ring -agnet

Force "y de%lects electrons do'n'ard R6R

1

Magnetic Field o% a Ring Magnet

Magnetic Field )B+

B

vyF


13/19

inetic ,nergy o% electron )H+

- -ass o% an electron )7g+ D13

The inetic ,nergy o% an ,lectron

In an electron gun given "y accelerating voltage ( is the accelerating voltage )(# HC+ 9!4!7(

2e 'ill use 3!7(

is the %unda-ental charge 1


14/19

14

,x.eri-ental *x /erivation I

This -eans into the .age

(y

Jx

B

Ge'tonKs nda' tells us:

2e can relate this to our -agnetic %orce:

Using ine-atics 'e 7no':

(

y


15/19

1;

,x.eri-ental *x /erivation II

JxB

0ince vyis large:

Ti-e it ta7es the electron to cross y:

0u""ing %or t# a# F:

(y

(


16/19

2e -easure -agnetic %ield 'ith a $auss Meter

The %ield has direction so 'e 'ill need to orient .ro"e .ro.erly

In this case parallelto the %ield lines )see /iagra-+

I% the %ield is negative %ield line is -oving a'ay %ro- the .ro"e

Not Important we are only interested in ||

1?

Measuring our Magnetic Field ,x.eri-entally

!


17/19

CRT technology 3 dots to -a7e a .ixel

These dots are .ri-ary colours and %or- other colours

Magnetic %ields cause de%lections o% charged .articles

The direction o% the %orce is given "y the right hand rule or cross .roduct

CRT technology uses -agnets to de%lect electrons on the screen

These la's can "e used to .redict the distance "et'een CRT dots

1@

0u--ary


18/19

CRT Picture 0lide Physics 4! ,lectron /e%lection


19/19

1D

uestions8

investigating crt technology

Documents