Lecture 1 6.973 Flat Panel Display Devices Outline • •
Overview of 6.973 Overview Flat Panel Display Devices
Course website— http://hackman.mit.edu/6973
Reading Assignment: Article by Alt and Noda, IBM Journal of Research and Development, Vol. 42, No. ¾, May/July 1998, p.315
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Classroom of the Future
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4165-8-14-98-1
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Information Capacity of Displays (BARS—Billions of Addressable Retinal Stimuli)
Alt, et al, IBM 6.973 Flat Panel Display Devices-Spring 2002
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Information Capacity of Displays (Pixel Count)
Resolution
Pixel
Ratio
Video Graphic Array (VGA) Super Vedio Graphic Array (SVGA) eXtended Graphic Array (XGA) Super eXtended Graphic Array (SXGA) Super eXtended Graphic Array plus (SXGA+) Ultra eXtended Graphic Array (UXGA)
640 x 480 x RGB
4:3
800 x 600 x RGB
4:3
1,024 x 768 x RGB
4:3
1,280 x 1,024 RGB
5:4
1,400 x 1,080 x RGB
4:3
1,600 x 1,200 x RGB
4:3
Display Devices, No. 21, Spring 2000, p. 41 6.973 Flat Panel Display Devices-Spring 2002
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Evolution of Notebook Displays
Kai Schleupen, IBM Research 6.973 Flat Panel Display Devices-Spring 2002
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High Resolution Displays a-Si AMLCDs
Kai Schleupen, IBM Research 6.973 Flat Panel Display Devices-Spring 2002
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Applications of Flat-Panel Displays SMALL FORMAT
Medical Defibrillator (mono)
Personal Digital Assistant (mono)
Car Navigation & Entertainment (color) Courtesy of PixTech
LARGE FORMAT
Desktop Monitor (color) 6.973 Flat Panel Display Devices-Spring 2002
Large Screen Television (color) Lecture 1
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Applications of Flat Panel Displays
Trium Handset
New Nokia Handset 6.973 Flat Panel Display Devices-Spring 2002
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Applications of Flat Panel Displays Trium Handset
New Nokia Handset 6.973 Flat Panel Display Devices-Spring 2002
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How Do Displays Work?
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Electronic display is a “Language Translator” that converts “Time Sequential Electrical Signals” into spatially and temporally configured light signal (images) useful to the viewer. Translation Function carried out by two intertwined sub-functions – Display element address wherein electrical signals are appropriately routed to the various display elements (similar to memory addressing) – Display element (pixel) converts the routed electrical signal at its input into light of certain wavelength and intensity (inverse of image capture)
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Classifications of Displays by Technology •
Displays could be classified into two broad categories – Photon Generator (Emissive Displays) – Photon Modulation (Light Valve Displays)
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Emissive Displays generate photons from electrical excitation of the picture element (pixels) Light Valve Displays spatially and temporally modulate the intensity pattern of the picture elements (pixels)
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Some Display Terminologies Term
Definition
Pixel
Picture elementThe smallest unit that can be addressed to give color and intensity
Pixel Matrix
Number of Rows by the Number of Columns of pixels that make up the deisplay
Aspect Ratio
Ratio of display width to display height; for example 4:3, 16:9
Resolution (ppi)
Number of pixels per unit length (ppi=pixels per inch)
Frame Rate (Hz)
Number of Frames displayed per second
Viewing Angle (°)
Angular range over which images from the display could be viewed without distortion
Diagonal Size
Length of display diagonal
Contrast Ratio
Ratio of the highest luminance (brightest) to the lowest luminance (darkest)
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Emissive Displays • •
Displays that generate photons when an electrical signal is applied between the terminals Energy causes excitation followed by excitation relaxation – Hole + Electron recombination – Exciton formation and annihilation – Relaxation of excited ions or radicals in a plasma
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The different types of Luminescence differ mostly in the way the holes and electrons are generated – holes and electrons are generated by UV in a phosphor which then recombine and generate red, green or blue light —Photoluminescence or Phosphorescence – holes and electrons injected by pn junction or generated by impact ionization or excitation which then recombine and generate red, green or blue light — Electroluminescence – holes and electrons generated by electron beam which then recombine and generate red, green or blue light — Cathodoluminescence
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Light Valve Displays • •
Displays that “spatially and temporally” modulate ambient lighting or broad source of light and redirect to the eye. Display element spatially changes the intensity of plane wave of light using – Refraction – Reflection – Polarization change
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These displays are part of a broader class of devices called Spatial Light Modulators which in general operate though local – – – –
Amplitude change Polarization change Phase change Intensity change
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Overview of 6.973 6.973: Introductory subject to flat panel devices and systems. •
Human Visual System and Perception – How do we convert light into visual signals? – Image capture & Visual Pathway
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Emissive Flat Panel Displays – How do we convert electrical signals to light and images? – Photon generator displays
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Light Valve Flat Panel Displays – How do we “re-direct” a broad light source into images? – Photon modulation displays
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Display Drivers and Large Area Electronics – How do we route the electrical signal to the picture element (pixel)? – Picture element (pixel) selection
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Human Visual System
• • • • •
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The Retina and PhotoReceptors (Cones & Rods) Visual Pathway Color Perception Tristhimus Color Coordinates Color Transformations
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Human Eye— Spectral Response 1.20
0.80
0.60
450
500
Yellow Orange 550
600
Red
0.00 400
Blue
0.20
Green
0.40
Violet
Relative Sensistivity
1.00
650
70
Wavelength (nm)
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Emissive Displays •
Theory of luminescence – Photoluminescence and Phosphorescence (holes and electrons generated by UV) – Electroluminescence (holes and electrons generated by pn junction injection or impact ionization or excitation) – Cathodoluminescence (holes and electrons generated by electron beam)
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Case Studies of Emissive Flat Panel Displays – Electroluminescence (Light Emitting Diode, Organic-Light Emitting Devices & In-organic ELectroluminescent Displays) – Cathodoluminescence (Cathode Ray Tube, Vacuum Florescent Display, Field Emission Display) – Photoluminescence (PLasma Displays)
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Light Valve Displays •
Theory of Spatial Light Modulators – – – –
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Amplitude change Polarization change Phase change Intensity change
Case studies of Light Valve Displays – Liquid Crystal Displays (active & passive matrix) – Deformable Mirror Displays – Membrane Mirror Displays – Electrophoretic Displays (E-Ink)
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Display Drivers and Large Area Electronics • •
Time sequential electrical signals meant for conversion need to be routed to the appropriate picture element (pixel) Typical flat panel displays are two-dimensional arrays of picture elements (pixels) that are individually addressed from the perimeter or the back. Methods of scanning include – Sequential addressing (CRTs) – Row scan addressing (AMLCDs and PMLCDs) – Random addressing (stroke mode CRTs)
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Row scanning of a matrix of pixels requires picture elements with nonlinear Luminance – Voltage (L-V) characteristics. If the Luminance-Voltage characteristics is linear (or is non-linear enough), a non linear switch element is required in series with the pixel. Examples are – Amorphous silicon thin film transistor – Poly-crystalline silicon thin film transistors
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Lecture, Problem Set and Lab Schedule
S
M
T
W
2/10 2/17 2/24 3/ 3 3/10 3/17 3/24 3/31 4/7 4/14 4/21 4/28 5/5 5/12
2/11 2/18 2/25 3/ 4 3/ 11 3/18 3/25 4/1 4/8 4/15 4/22 4/29 5/6 5/13
2/12 Intro 2/19 No Class 2/26 Luminescence 3/ 5 EL 3/12 CL 3/19 SLM 3/26 No Class 4/2 LC 4/9 Drivers 4/16 No Class 4/23 Backplanes 4/30 AMLCD 5/7 Micro-Displays 5/14 Project
2/13 2/20 2/27 3/6 3/13 3/20 3/27 4/3 4/10 4/17 4/24 5/1 5/8 5/15
R 2/7 2/14 Vision 2/21 Vision 2/28 Luminescence 3/7 EL 3/14 PL 3/21 LC 3/28 No Class 4/4 PMLCD 4/11 Backplanes 4/18 Backplanes 4/25 OTFT 5/2 Reflective LCD 5/9 Guest Lecture 5/16 Project
F 2/8 2/15 2/22 3/1 3/8 3/15 3/22 3/29 4/5 4/12 4/19 4/26 5/3 5/10 5/17
S 2/9 2/16 2/23 3/2 3/9 3/16 3/23 3/30 4/6 4/13 4/20 4/27 5/4 5/11 5/18
Legend No Assignment No Class Homework Laboratory Design Project
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Display Devices Built in Lab These are devices that will be built in the laboratory sessions See last years website for lab info http://hackman.mit.edu/LabHandouts.html
EL Backlight
Liquid Crystal Display 6.973 Flat Panel Display Devices-Spring 2002
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Cathode Ray Tube CRT Display Cathode
Phosphor Screen
Anode
Electrons beam “boiled off a metal” by heat (thermionic emission) is sequentially scanned across a phosphor screen by magnetic deflection. The electrons are accelerated to the screen acquiring energy and generate light on reaching the screen (cathodoluminescence)
Courtesy of PixTech 6.973 Flat Panel Display Devices-Spring 2002
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Thin-CRT Cathode
FED Display
Phosphors
Anode
Courtesy of PixTech
In principle similar to the CRT except that it uses a two-dimensional array of electron sources (field emission arrays) which are matrix addressed allowing the vacuum package to be thin 6.973 Flat Panel Display Devices-Spring 2002
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Thin-CRTs An Early Candescent 13.2” SVGA ThinCRT Display
Courtesy of Candescent Technologies 6.973 Flat Panel Display Devices-Spring 2002
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Plasma Displays
Weber, SID 00 Digest, p. 402.
• Electrons are accelerated by voltage and collide with gasses resulting in ionization and energy transfer • Excited ions or radicals relax to give UV photons • UV photons cause hole-electron generation in phosphor and visible light emission 6.973 Flat Panel Display Devices-Spring 2002
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Plasma Displays
Weber, SID 00 Digest, p. 402.
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Electroluminescent Display 12µm 1280 x 1024 AMEL Display Courtesy of Planar Technologies
2k AMEL Development
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Organic Light Emitting Diode
Rajeswaran et al., SID 00 Digest, p. 974 6.973 Flat Panel Display Devices-Spring 2002
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Organic Light Emitting Diode
Rajeswaran et al., SID 00 Digest, p. 974 6.973 Flat Panel Display Devices-Spring 2002
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Digital Mirror Device Courtesy of Texas Instruments
Applied voltage deflects Mirror and hence direct light
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Digital Mirror Device
Courtesy of Texas Instruments 6.973 Flat Panel Display Devices-Spring 2002
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Liquid Crystal Displays Liquid Crystals rotate the plane of polarization of light when a voltage is applied across the cell
Courtesy of Silicon Graphics 6.973 Flat Panel Display Devices-Spring 2002
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Color Active Matrix LCD
Courtesy of Silicon Graphics 6.973 Flat Panel Display Devices-Spring 2002
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22.2”-QUXGAW AMLCD (Bertha)
Kai Schleupen, IBM Research 6.973 Flat Panel Display Devices-Spring 2002
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22.2”-QUXGA-W AMLCD (Bertha)
Kai Schleupen, IBM Research 6.973 Flat Panel Display Devices-Spring 2002
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Bistable Cholesteric LCDs Pixel States P/2
Black State
Color Reflective Planar State
4 Pixels 6.973 Flat Panel Display Devices-Spring 2002
Courtesy of Kent Displays Lecture 1
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1/4 VGA, Full Color Ch-LCD Photographed in Sunlight
Courtesy of Kent Displays 6.973 Flat Panel Display Devices-Spring 2002
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