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See It Now: A Primer on LCD, DLP, LCoS, and Plasma Technologies Pete Putman, CTS, ISF Publisher, HDTVexpert.com Contributing Editor, Pro AV.

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Presentation on theme: "See It Now: A Primer on LCD, DLP, LCoS, and Plasma Technologies Pete Putman, CTS, ISF Publisher, HDTVexpert.com Contributing Editor, Pro AV."— Presentation transcript:

1 See It Now: A Primer on LCD, DLP, LCoS, and Plasma Technologies Pete Putman, CTS, ISF Publisher, HDTVexpert.com Contributing Editor, Pro AV

2 The CRT is Getting Old –Technology is over 100 years old –Monochrome CRTs used from 1910s –Color CRTs developed in early 1950s (RCA) –Monochrome tubes were used in front projectors in 1980s – 90s (7, 8, 9) –Manufacturing has largely moved to China High-volume, low-margin product Thomson TTE, TCL, and others make them

3 CRT Imaging Process –Low-voltage emission of electrons –High-voltage anode attracts electrons –Electrons strike phosphors, causing them to glow brightly –Color CRTs use three electron guns –Projection CRTs use single-color phosphors –Response of CRT is linear for wide grayscales

4 CRT Imaging Process

5 CRT Performance Advantages: –CRTs can scan multiple resolutions –Wide, linear grayscales are possible –Precise color shading is achieved –CRTs have no native pixel structure Drawbacks: –Brightness limited by tube size –Resolution (spot size) linked to brightness –Heavy, bulky displays for small screen sizes

6 What Will Replace The CRT? Contenders for direct-view applications: –Liquid-crystal displays (LCDs) –Plasma display panels (PDPs) Contenders for front/rear projection applications: –Liquid-crystal on silicon (LCoS) Silicon Xtal Reflective Device (SXRD) Digital Image Light Amplifier (D-ILA) –Digital Light Processing (DLP)

7 Transmissive Liquid-Crystal (LCD) Displays

8 LCD Display Technology Liquid-crystal displays are transmissive LC pixels act as light shutters Current LCD benchmarks: –Sizes to 82 (prototypes) –Resolution to 1920x1080 pixels –Brightness > 500 nits Power draw < plasma in same size Weight < plasma in same size

9 LCD Imaging Process Randomly arranged LCs pass light (off ) Aligned LCs block light (on) This effect is called birefringence Principle is the same for low-temperature and high-temperature polysilicon LCDs, and liquid crystal on silicon (LCoS) panels

10 LCD Imaging Process

11 LCD Imaging Process Building a Better Mousetrap The Sharp Approach The LG Philips Approach The Samsung Approach

12 Real-World LCD Benchmarks A review sample 45-inch LCD monitor delivered 304 nits (89 foot-Lamberts) with ANSI (average) contrast measured at 217:1 and peak contrast at 234:1 Typical black level was 1.6 nits (8x CRT) Native resolution – 1920x1080 Power consumption – watts over a 6- hour interval (total of kWh)

13 Real-World LCD Benchmarks Color Rendering –Test panel uses CCFLs –Gamut is smaller than REC 709 coordinates –Green way undersaturated –Red, blue are closer to ideal coordinates

14 LCD Display Technology Technology Enhancements: –Better color through corrected CCFLs, LEDs –Improved black levels (compensating films) –Higher contrast (pulsed backlights) –Wider viewing angles (compensating films) –Higher resolution 37) –Improved LC twist times (various)

15 Emissive Imaging: Plasma Display Panels (PDPs)

16 PDP Technology Plasma displays are emissive Current PDP benchmarks: –Sizes to 103 –Resolution to 1920x1080 –Brightness >100 nits (FW), 1000 nits peak Power draw 15%-20% > same size LCD Weight 20%-25% > same size LCD

17 Plasma Imaging Process Three-step charge/discharge cycle –Uses neon – xenon gas mixture – V AC discharge in cell stimulates ultraviolet (UV) radiation –UV stimulation causes color phosphors to glow and form picture elements –Considerable heat and EMI are released

18 Plasma Imaging Process

19 PDP Rib Structure (Simple)

20 Deep Cell Structure (Advanced) Waffle-like structure Higher light output Less light leakage between rib barriers Developed by Pioneer

21 Plasma Tube Structure (Future?) Phosphors, electrodes, and Ne/Xe gas combined into long tubes Reduces cost of larger screens Flexible displays? Developed by Fujitsu

22 Real-World Plasma Benchmarks A review sample 50-inch plasma monitor measured from 93 nits (full white) to 233 nits (small area), with ANSI (average) contrast measured at 572:1 and peak contrast at 668:1 Typical black level.21 nits (closer to CRT) Native Resolution x768 Power consumption – watts over a 6- hour interval (total of kWh)

23 Real-World Plasma Benchmarks Color Rendering –Gamut is smaller than REC 709 coordinates –Green somewhat undersaturated –Red, blue are very close to ideal coordinates

24 Plasma Display Technology Technology Enhancements: –Wider color gamuts (films, phosphors) –Improved lifetime (gas mixtures) –Higher resolution 50) –Resistance to burn-in (change in gas mixture)

25 Reflective Imaging: Digital Light Processing (DLP) Displays

26 DLP Imaging Digital micromirror device (DMD) used Rapid on-off cycling of mirrors (pulse-width modulation) builds grayscale image Color added and blended: –With color wheel (single chip) –With polarizing beam splitter (3-chip) Lens projects image to screen

27 Pulse-Width Modulation Technique to re-create grayscale intensities digitally with DMD DMD mirror positions are ON (1) and OFF (0) Rapid cycling between ON and OFF mirror positions produces grayscale values Total mirror tilt is 12 o

28 Pulse-Width Modulation PWM grayscale values related to on/off ratios In a given interval: –If more ON DMD tilt positions than OFF, lighter value results –If more OFF DMD tilt positions than ON, darker value results ON > OFF OFF > ON

29 DLP Imaging – Single Chip

30 DLP Imaging – Three-Chip

31 Three-Chip Imaging Uses Polarizing Beam Splitter (PBS) for high- power three-chip DLP projectors Light travels in both directions through it Red, green, and blue colors added in PBS

32 Digital Micromirror Devices DMDs can be made in many sizes 4:3 - 16:9 aspect ratios are supported Simple light path with single chip Pure digital light modulator SXGA (left) and XGA (right) DMDs

33 Reflective Imaging: Liquid-Crystal on Silicon (LCoS) Displays

34 LCoS Imaging LCoS is a reflective imaging system Switching transistors are on backplane Greater imaging surface available – higher fill factor than HTPS LCD Easier to achieve high pixel density in small panels than with HTPS LCD

35 LCoS Panel Cutaway

36 LCoS Optical Engine

37 LCoS Panels JVC Direct Drive Digital Light Amplifier (D-ILA) is LCoS technology Resolutions to 4K High fill factor (>90%) Used in front and rear projection systems JVC 4096x2160 D-ILA Panel

38 LCoS Panels Sony Silicon Xtal Reflective Device (SXRD) also LCoS technology Panels made with both 2K and 4K resolution Used in front/rear projection systems Sony 4096x2160 SXRD panel

39 Image Quality Parameters

40 Brightness/Contrast/Grayscale Pixel-based imaging breaks the link between brightness and resolution Peak brightness levels to 1000 nits in LCD and plasma achieved, > 10,000 lumens in LCoS and DLP projectors Average contrast to 500:1 (LCD, LCoS) Average contrast > 1000:1 (DLP, plasma)

41 Color and White Balance CRT offers pure RGB color blending and clean white balance Plasma color balance affected by gas mixture and UV emissions LCD, LCoS, DLP projectors dependent on light source (short-arc lamps) –UHP/UHE less expensive, color is tricky –Xenon more costly, color quality is superior

42 Illuminants: Projection Lamps Short-arc mercury vapor lamps UHP, UHE, SHE are common designations Uneven spectral output Life 1000–3000 hours 150W UHP Lamp

43 Illuminants: Projection Lamps Short-arc xenon lamps Higher wattage than comparable UHP lamps Evenly-distributed spectral output Life hours 325W Xenon Lamp

44 Illuminants: Cold-Cathode Backlights Compact design Uneven spectral energy – high in green/blue Bright sources of diffuse lighting Life 50,000 – 60,000 hrs Not green! (contains Hg) Two CCFL Lamps

45 Illuminants: LED Backlights Compact design Evenly-distributed spectral energy LED matrix is weighted LED life estimated at 50,000 – 100,000 hours LEDs are current hogs GRB LED Array

46 Illuminants: Plasma Phosphors Rare earth formulations similar to CRT Red, blue easy to saturate; green is tougher Ne/Xe mixture affects color balance and life (estimated 40,000 – 60,000 hrs) Close-up of RGB Phosphors

47 See It Now: A Primer on LCD, DLP, LCoS, and Plasma Technologies Pete Putman, CTS, ISF Publisher, HDTVexpert.com Contributing Editor, Pro AV


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