# Lecture 7: Displays Digital Displays Cathode Ray Tubes

Lecture 7: Displays Digital Displays Cathode Ray Tubes Flat Panel Displays February 27, 2020 Introduction to Engineering Electronics 1 Summary of What We Have Learned Ohms Law Resistor Combinations What a Diode Does Transistors as Switches Op-Amp Configurations February 27, 2020

Introduction to Engineering Electronics 2 Ohms Law V I R Kirchoffs Voltage Law Kirchoffs Current Law I IN R Series Equivalent Parallel

Equivalent February 27, 2020 V 0 1 R EQ EQ IOUT R 1 R 2 . . . R N 1 1

1 . . . R1 R2 RN Introduction to Engineering Electronics 3 Diode V-I Characteristic For ideal diode, current flows only one way Real diode is close to ideal Ideal Diode February 27, 2020 Introduction to Engineering Electronics

4 February 27, 2020 Introduction to Engineering Electronics 5 Op-Amp February 27, 2020 Introduction to Engineering Electronics 6 Ideal Op-Amp Continued

Bandwidth is also infinite. Thus, an ideal op-amp works the same at all frequencies. February 27, 2020 Introduction to Engineering Electronics 7 Golden Rules for Op-Amps The output attempts to do whatever is necessary to make the voltage difference between the two inputs zero. (Negative Feedback is Required) The inputs draw no current. February 27, 2020 Introduction to Engineering

Electronics 8 Op-Amp Configurations Buffer or Voltage Follower No voltage difference between the output and the input Draws no current, so it puts no load on the source Used to isolate sources from loads February 27, 2020 Introduction to Engineering Electronics 9 Op-Amp Configurations Non-Inverting Amplifier

V O U T V IN R1 1 R2 Note that this formula is different in the lab write up February 27, 2020 Introduction to Engineering Electronics

10 Op-Amp Configurations Inverting Op-Amp V February 27, 2020 O U T V R IN f R1 Introduction to Engineering

Electronics 11 Binary Numbers 0 1 2 3 4 5 0000 0001 0010 0011 0100 0101 6 7 8 9

10 11 0110 0111 1000 1001 1010 1011 B y te L o w e r N ib b le U p p e r N ib b le B it 7 B it 6 B it 5

B it 4 B it 3 B it 2 B it 1 B it 0 1 0 1 1

0 1 1 1 2 128 February 27, 2020 7 + 2 + 0 6

+ + 2 5 + 32 + 2 4 + 16 + 2 3

0 + + 2 2 4 2 + + 1 2 +

2 + Introduction to Engineering Electronics B in a r y num ber 0 =183 1 = 183 12 Astable and Monostable Multivibrators

What are they good for? Astable: clock, timing signal Monostable: a clean pulse of the correct height and duration for digital system February 27, 2020 Introduction to Engineering Electronics 13 555 Timer The correct frequency is given by 1 1 .4 4 f 0 .6 9 3 ( R 1 2 R 2 ) C 1 ( R 1 2 R 2 ) C 1 Note the error in the figure

February 27, 2020 Introduction to Engineering Electronics 14 From What We Have Seen So Far, How Would We Make a Display? LEDs in some kind of an array How to arrange them? How to control them? What is the purpose of the display? How much should it cost? February 27, 2020 Introduction to Engineering Electronics 15

7 Segment Displays Binary inputs are converted to a decimal number display by turning on a set of 7 LEDs February 27, 2020 Introduction to Engineering Electronics 16 7 Segment Displays Common cathode at the right and common anode at the left February 27, 2020 Introduction to Engineering Electronics

17 7 Segment Displays 5V + 1 10 1 2 9 7 - 6 5 4 3

CL CLK LD TE PE 0-9 circuit 15 CO P4 P3 P2 P1 14 13 12 11

Q1 Q2 Q3 Q4 7 1 2 6 2 14161 1 13 1Y 2Y VCC

VCC 1A 1B 1C 1D 2A 2B 2C 2D 2 3 4 5 9 10 11 12 5V 3

4 5 8 A B C D LT BI LE GND 1 16 Vcc a b c d e

f g 13 12 11 10 9 15 14 MC14511-b 14 a b 12 c 10

d 4 2 13 e CAT4 CAT3 CAT2 CAT1 f g 6 LDP RDP

16 11 5 3 9 SEVSEG-b 14012-chip This is the 0-9 counting circuit you will be building in the lab. Note that it has to count and then convert the binary to show decimal February 27, 2020 Introduction to Engineering Electronics 18 Displays Applications

7 Segments are excellent for displaying simple alphanumeric information multimeters, clocks, etc. More complex displays are needed to show images computer displays, televisions, etc. February 27, 2020 Introduction to Engineering Electronics 19 2 Minute Quiz Name________________ Sec___ Give three examples of electronic displays What is a pixel? True or False

Blue light is higher energy than red light Most colored light is not produced directly Solid state light is generally produced directly February 27, 2020 Introduction to Engineering Electronics 20 Dividing Images Into Pixels Second image is blown up many times to show the individual pixels February 27, 2020 Introduction to Engineering Electronics

21 Dividing Images Into Pixels The second image is blown up a bit less but pixels are still obvious February 27, 2020 Introduction to Engineering Electronics 22 Dividing Images Into Pixels The second image is sampled more coarsely February 27, 2020 Introduction to Engineering Electronics

23 Dividing Images Into Pixels Black and white or single color displays are easier to implement February 27, 2020 Introduction to Engineering Electronics 24 Dividing Images Into Pixels Images can be constructed by scanning across them, line-by-line The original image is encoded in this manner (e.g. this is the way a scanner or copier works) by, say, starting at the upper left and going

line by line to the lower right February 27, 2020 Introduction to Engineering Electronics 25 Plasma Displays Large, bright, flat panel display View from a wide angular range Designed for HDTV Available from many companies February 27, 2020 Introduction to Engineering Electronics 26

Plasma Displays High voltage discharge creates high energy photons (UV) that excite phosphors February 27, 2020 Introduction to Engineering Electronics 27 Plasma Displays Note the patterns of the address and display electrodes To excite an address, both voltages must be applied February 27, 2020 Introduction to Engineering

Electronics 28 Plasma Displays Fujitsu ALIS display More complex electrodes but better use of surface area for display February 27, 2020 Introduction to Engineering Electronics 29 Plasma Displays Discharge region geometry and voltages

February 27, 2020 Introduction to Engineering Electronics 30 Displays: CRT In a CRT, an electron beam excites the phosphor rather than a UV photon The beam is directed to a spot on the surface using sweep plates February 27, 2020 Introduction to Engineering Electronics 31 Displays: CRT

Three separate electron guns are required to produce a color picture February 27, 2020 Introduction to Engineering Electronics 32 Displays: CRT At the left is the layout of the mask and phosphors At the right is the scanning sequence February 27, 2020 Introduction to Engineering Electronics

33 Displays: CRT A large variety of configurations are used by manufacturers Look carefully at the screen of your TV February 27, 2020 Introduction to Engineering Electronics 34 Image From My TV February 27, 2020 Introduction to Engineering Electronics

35 Same Image Enlarged to Show Screen February 27, 2020 Introduction to Engineering Electronics 36 Same Image Enlarged Further February 27, 2020 Introduction to Engineering Electronics 37

Same Image Enlarged Further February 27, 2020 Introduction to Engineering Electronics 38 Unsmoothed Image Enlarged Further February 27, 2020 Introduction to Engineering Electronics 39 Displays: Early TV Allen Dumont

B.S.E.E. RPI 1924 February 27, 2020 Introduction to Engineering Electronics 40 Displays: Dumont Developed the first practical CRT (previous versions lasted only 10s of hours) First company to market home TV receiver in 1938 (previous slide) Dumont network until 1956 It could not compete with radio networks (poorly funded) Broadcast Jackie Gleason, first sporting events, but shows were bought by big 3 networks Dumont was one of broadcastings first millionaires February 27, 2020

Introduction to Engineering Electronics 41 Where Will You See This Material Again? 7 Segment Displays: Many courses CRT: ECSE-2100 Fields and Waves I Digital Imaging: ECSE-4540 Voice and Image Processing RF Circuitry: ECSE-4060 Communications Circuits Plasmas: ECSE-4320 Plasma Engineering Optics: ECSE-4630 Lasers and Optical Engineering and ECSE-4640 Optical Communications and Integrated Optics February 27, 2020 Introduction to Engineering Electronics

42 Imaging Tools Mathworks Image Processing Toolboxes http://www.mathworks.com/products/im age February 27, 2020 Introduction to Engineering Electronics 43 Charged Particle Accelerators Fermilab Medical Accelerator February 27, 2020

Introduction to Engineering Electronics 44

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