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Lecture 7: Displays

Lecture 7: Displays. Digital Displays Cathode Ray Tubes Flat Panel Displays. Summary of What We Have Learned. Ohm’s Law Resistor Combinations What a Diode Does Transistors as Switches Op-Amp Configurations. Ohm’s Law. Kirchoff’s Voltage Law. Kirchoff’s Current Law. Series Equivalent.

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Lecture 7: Displays

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  1. Lecture 7: Displays Digital Displays Cathode Ray Tubes Flat Panel Displays Introduction to Engineering Electronics K. A. Connor

  2. Summary of What We Have Learned • Ohm’s Law • Resistor Combinations • What a Diode Does • Transistors as Switches • Op-Amp Configurations Introduction to Engineering Electronics K. A. Connor

  3. Ohm’s Law Kirchoff’s Voltage Law Kirchoff’s Current Law Series Equivalent Parallel Equivalent Introduction to Engineering Electronics K. A. Connor

  4. Diode V-I Characteristic • For ideal diode, current flows only one way • Real diode is close to ideal Ideal Diode Introduction to Engineering Electronics K. A. Connor

  5. Introduction to Engineering Electronics K. A. Connor

  6. Op-Amp Introduction to Engineering Electronics K. A. Connor

  7. Ideal Op-Amp Continued • Bandwidth is also infinite. Thus, an ideal op-amp works the same at all frequencies. Introduction to Engineering Electronics K. A. Connor

  8. 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. Introduction to Engineering Electronics K. A. Connor

  9. 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 Introduction to Engineering Electronics K. A. Connor

  10. Op-Amp Configurations • Non-Inverting Amplifier Note that this formula is different in the lab write up Introduction to Engineering Electronics K. A. Connor

  11. Op-Amp Configurations • Inverting Op-Amp Introduction to Engineering Electronics K. A. Connor

  12. Binary Numbers 0 0000 1 0001 2 0010 3 0011 4 0100 5 0101 6 0110 7 0111 8 1000 9 1001 10 1010 11 1011 128 + 0 + 32 + 16 + 0 + 4 + 2 + 1 = 183 Introduction to Engineering Electronics K. A. Connor

  13. 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 Introduction to Engineering Electronics K. A. Connor

  14. 555 Timer • The correct frequency is given by Note the error in the figure Introduction to Engineering Electronics K. A. Connor

  15. 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? Introduction to Engineering Electronics K. A. Connor

  16. 7 Segment Displays • Binary inputs are converted to a decimal number display by turning on a set of 7 LEDs Introduction to Engineering Electronics K. A. Connor

  17. 7 Segment Displays • Common cathode at the right and common anode at the left Introduction to Engineering Electronics K. A. Connor

  18. 7 Segment Displays • 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 Introduction to Engineering Electronics K. A. Connor

  19. 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. Introduction to Engineering Electronics K. A. Connor

  20. 2 Minute QuizName________________ 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 Introduction to Engineering Electronics K. A. Connor

  21. Dividing Images Into Pixels • Second image is blown up many times to show the individual pixels Introduction to Engineering Electronics K. A. Connor

  22. Dividing Images Into Pixels • The second image is blown up a bit less but pixels are still obvious Introduction to Engineering Electronics K. A. Connor

  23. Dividing Images Into Pixels • The second image is sampled more coarsely Introduction to Engineering Electronics K. A. Connor

  24. Dividing Images Into Pixels • Black and white or single color displays are easier to implement Introduction to Engineering Electronics K. A. Connor

  25. 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 Introduction to Engineering Electronics K. A. Connor

  26. Plasma Displays • Large, bright, flat panel display • View from a wide angular range • Designed for HDTV • Available from many companies Introduction to Engineering Electronics K. A. Connor

  27. Plasma Displays • High voltage discharge creates high energy photons (UV) that excite phosphors Introduction to Engineering Electronics K. A. Connor

  28. Plasma Displays • Note the patterns of the address and display electrodes • To excite an address, both voltages must be applied Introduction to Engineering Electronics K. A. Connor

  29. Plasma Displays • Fujitsu ALIS display • More complex electrodes but better use of surface area for display Introduction to Engineering Electronics K. A. Connor

  30. Plasma Displays • Discharge region geometry and voltages Introduction to Engineering Electronics K. A. Connor

  31. 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 Introduction to Engineering Electronics K. A. Connor

  32. Displays: CRT • Three separate electron guns are required to produce a color picture Introduction to Engineering Electronics K. A. Connor

  33. Displays: CRT • At the left is the layout of the mask and phosphors • At the right is the scanning sequence Introduction to Engineering Electronics K. A. Connor

  34. Displays: CRT • A large variety of configurations are used by manufacturers • Look carefully at the screen of your TV Introduction to Engineering Electronics K. A. Connor

  35. Image From My TV Introduction to Engineering Electronics K. A. Connor

  36. Same Image Enlarged to Show Screen Introduction to Engineering Electronics K. A. Connor

  37. Same Image Enlarged Further Introduction to Engineering Electronics K. A. Connor

  38. Same Image Enlarged Further Introduction to Engineering Electronics K. A. Connor

  39. Unsmoothed Image Enlarged Further Introduction to Engineering Electronics K. A. Connor

  40. Displays: Early TV Allen Dumont B.S.E.E. RPI 1924 Introduction to Engineering Electronics K. A. Connor

  41. 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 Introduction to Engineering Electronics K. A. Connor

  42. 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 Introduction to Engineering Electronics K. A. Connor

  43. Imaging Tools • Mathworks Image Processing Toolboxes http://www.mathworks.com/products/image Introduction to Engineering Electronics K. A. Connor

  44. Charged Particle Accelerators • Fermilab • Medical Accelerator Introduction to Engineering Electronics K. A. Connor

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