?????CRT?????

1
??2 ?????????????? (????15/16)
?? ???????(cathode ray tube, CRT)????????(E)???(B
)????????,?????????(e/m?) ?? Lorentz force F
q(E v x B) SI unit N C(V/m)
C(m/s).T

• ?????CRT?????
• ????G
• ????F
• ????A (???V1)
• ????(??)?????
• ????(??)?????
• Z?????????
• ???
• ?????(CRT)??????
• ?????(CRT)????C

?????CRT?????
2
??????????Operation Principle of CRT

• I. ?????????????(4,5)????????
• ???????????(8)???C(9)???????
• ?????G(1), ????F(2)?????A(3)(???V1)?
• ???Z??(6)?????,mvz2/2 eV1 ? vz (2eV1/m)1/2
• ???????(XY?)(7)??????,??????

???? m 9.11 x 10-31 kg ?? q -e -1.60 x
10-19 C
As V4 0 V5 0
?????CRT?????
3
Cathode Ray Tube(CRT)

• The electrons are deflected in various directions
  by two sets of plates.
• The placing of charge on the plates creates the
  electric field between the plates and allows the
  beam to be steered.

• Commonly used to obtain a visual display of
  electronic information in oscilloscopes, radar
  systems, televisions, etc..
• Be a vacuum tube in which a beam of electrons is
  accelerated and deflected under the influence of
  electric or magnetic fields.

4
Cathode Ray Tube (CRT) - is one of the main
elements of an oscilloscope.

• A CRT is commonly used to obtain a visual display
  of electronic information in oscilloscopes, radar
  systems, televisions, etc.
• The CRT is a vacuum tube in which a beam of
  electrons is accelerated and deflected under the
  influence of electric or magnetic fields.
• The tubes are produced with electrostatic and
  electromagnetic control, where electrostatic or
  magnetic fields deviate the electron beam
  respectively.
• The principle scheme of CRT has electrostatic
  control as well as the motion of the electrons in
  the beam drawing a sinusoid on the screen of
  oscilloscope.

5
Configuration of CRT

• CRT consists of 6 sections
• Glass bulb evacuated to a high vacuum (???)
• Cathode (a source of electrons,?????)
• Cathode heater (?????)
• Electrodes for brightness and focus control,
  several accelerating anodes (????????????)
• Pairs of horizontal and vertical capacitor plates
  deviating the electron beam
• Fluorescing screen (???)

6
Discharge Tube

• It was observed that whenever the glass tube
  filled with air at low pressure and
• sealed with electrodes at both the ends was
  subjected to about 10,000 volts of electricity,
• a strange glow was produced around the edges of
  the wide end of the glass tube, irrespective of
  the type of gases present in it.
• The glass tube with sealed electrodes is called
  discharge tube.

Discharge Tube
Electron Gun
7
Cutaway rendering of a color CRT

1. Electron guns
2. Electron beams
3. Focusing coils
4. Deflection coils
5. Anode connection
6. Mask for separating beams for red, green, and
   blue part of displayed image
7. Phosphor layer with red, green, and blue zones
8. Close-up of the phosphor-coated inner side of the
   screen

8
CATHODE-RAY TUBE (CRT)- is one of the main
elements of an oscilloscope.

• One of anodes, which accelerate the electrons, is
  placed close to the screen.
• The high positive voltage is applied to this
  electrode.
• Under the action of the applied voltage the
  electrons are moved with acceleration from
  cathode to anode.
• In the absence of the voltage applied to
  deviating plates of the capacitor the electron
  beam will be incident on the screen in the center
  brightening a point in the fluorescing layer.
• In oscilloscope the analyzed signal after
  amplification is applied to vertical deviating
  plates, while the periodic sawtooth signal is
  applied to horizontal plates.

9
http//physics-animations.com/Physics/English/osc_
tmp.htm

• As a result the electron beam "draws"  the
  dependence of the investigated signal on time on
  the screen of the tube.
• Reaching the right side of the screen the beam
  has to be returned to an initial point at the
  left side.
• Thus, if CRT is not blanked during this retrace,
  then the beam will leave a track crossing the
  image of investigated signal.
• For this reason, during retrace a negative
  voltage is applied to control electrode situated
  near to cathode and electrons are locked by such
  a way at the electron gun.
• As a result, the electron beam will be
  discontinuous, as shown in animation.

10
Related Web Sites for CRT Animation

• http//highered.mcgraw-hill.com/sites/0072512644/s
  tudent_view0/chapter2/animations_center.html
• http//physics-animations.com/Physics/English/osc_
  tmp.htm
• http//www.sciencemuseum.org.uk/on-line/electron/
  section2/shockwave2.asp
• The Cathode Ray Tube site http//members.chello.n
  l/h.dijkstra19/page3.html
• How Television Works http//www.howstuffworks.co
  m/tv.htm/printable

11
2. ??????????? ??????X(4)?????Y(5)??????,???
???(E),??????,???Y?L, ????d, ?????V2 (E
V2/d),???????????D,????Y????SE,????(XY?)?Y? SE
???????
X?????? Y?????
X, Y??????
12
3. ??????????? ????Y?????? f ?/2? 1/T
???,??????????l??? Note???? Vrms 110 V, f
60 Hz
13
4. ????????? ???????????????(B)??????
????x?? (?L),??????????? D ????Y???? SB (?
Sm) ???(XY?)Y??SB???? 5. ????????????
??????? SE SB 0 eE evzB
vz E/B ?? SE ? SB
???????? (e/m) ?
14
???? I. ??????? 1. ?????(X 60 mm, Y 54 mm,
D 115 mm, L 11 mm, d 1.65 mm)
??CRT??(Unilab 031.502) X?X?????
Y?Y????? A1??????? Z??? 2.
CRT???CTR????(032.332) ???CRT??(tube supply)
??????! ????, ???????
????(off)(??) 3. ??CRT??? ??(brill)(????)
???(focus)(????)
15
II????? 1. ???(amplifier)(2)(032.842)?CRT?????(1)
(032.332)?aux unit????(6 V) 2. ??????
?????(1)?????(6 Vrms)?????? ????A
(alternating coupling)??? ???C (common) AC
??ac????(?????) DC ????D (direct
coupling) ac/dc?????? 3.
????X/Y????CRT??(3) (031.502)???Y???? 4.
????????(gain)? ?? (shift) ?,?????Y??
????????/????? l 2Vm (???)
Y???(sensitivity) 23 V/1 cm (Q)?????T?
(1)
(3)
(2)
16
III.????????? 1. ?????(2)??????? (??????) 2.
?????(2)??????? (??????)?????
???(3)??DC?(??) 3. ?????(3)?????
CRT?????????(5) (???????t)(???)
17
(1)
3. (5)??Y?????? ??????(4)???DC?
(???????V) 4. ?????A???? ?????(2)(032.892)
(time base generator) ?????(sync) 5.
??CRT???Y(X) V(t), ???(Vm)???(T)
(2)
(3)
(4)
(5)
18

• IV. ????
• ???????????(5) ??????????(2) (031.402),????N
  3000? 3000??
• ??????(4)????(3) ???????(I)??,???B ?
  NI,?????B??
• 3.??????????CRT ??(1)?CRT??
• 4.???????????e/m???

(1)
(2)
(5)
(3)
(4)
19
??3 ????? (????17)
?? ?????(oscilloscope)???????? ??
????????????????? (?) ??? TRIO CS-1022
(??B) 1. ?????(CRT)?? (Z???) (????)
??????(power) (13,14) (????,????) ??(ground,
GND) (15) ????,?????? (????,????) ??(probe
adjust) (16) ??, f 1 kHz, Vp-p 2Vm
0.5 V ????(trace rotation) (17) ??????/????
??(focus) (18) ???? ??(intensity) (19)
???? (3-1)

20
????? (?) TRIO CS-1022 Y -- X
l
Z l T (3-2)
21
2. ??(vertical)(Y?)???(horrizontal)(X?)??
(?Y??) ????(position) (1) ???? (???????)
??/????(variable/cal) (2) ????(cal)??,
????? 1 mV/? 5 V/? ???(sensitivity/volts)
(3) ??????? ????(ac-GND-dc) (4) ac
alternating coupling (??) GND no signal
(????) dc direct coupling (????)
??(input) (5) BNC??? ???? (mode) (12)
ch 1 Y signal only ch 2 X signal
only add XY alt, chop (????)
(3-3)

22
3. ??(T)?? (X???) ????/??(trig level/slope)
(22) ???? (/0) ????(trig coupling)
(23) ac ???(trig source) (24) ch
1 Y ?? (???????) ch 2 X line
(????) ext (????) (?21) ????(trig
mode) (25) auto (????) norm (??)
X Y ??/????(variable/cal) (26)
????(cal)??, ????? 0.2 ms/? 0.5 s/?
????(sweep time) (27) ??????? ????(position)
(28) ???? (???????) (3-4)

23
??????(block diagram) (?) National
VP-5107T Y X/ T
calibrator power/Z (3-5)
24
???????(signal generator) (?) TRIO
AG-203 ??(power) (1,2) (????) ????(attenuation)
0 - -50 dB 6????? (3) I(dB)
10.log10(I/I0) 0 dB 1, -10 dB 10-1 -20 dB
10-2, -30 dB 10-3 -40 dB 10-4, -50 dB
10-5 ????(output) (4) ??(wave form) ???,??
(5) ??(frequency) 10 Hz 1 MHz 5?????(range)
(6,8,9,10) x1 (10-100 Hz), x10, x100 x1k,
x10k (100 kHz 1 MHz) ??(amplitude) ????
(7) (3-6)
25
?? 1. ?????? 2. ??????????? 3. ?????????? 4.
X-Y?? X,Y?????? ???????? Vx Vy 5.
??(f)?? Y?????? Vy(t)
Vmsin(2pf.t) (3-7)