Residential Audio & Video Systems Copyright © 2005 Heathkit Company, Inc. All Rights Reserved Presentation 9 – Home Theater Video Display Systems

2 Objectives At the end of this presentation, you will be able to:

3 Explain the difference between direct view and projection TV and list examples of both. Define aspect ratio and give two examples commonly used in TV. Explain how the TV screen size is usually measured.

4 Describe the construction and basic operation of the color cathode ray tube (CRT) TV display. Describe the construction and basic operation of the plasma flat panel TV display. Describe the construction and basic operation of the liquid crystal display (LCD) flat panel display.

5 The Home Theater System Video Display Surround Sound A/V Receiver Stereo Hi/Fi VCR or DVD Player Surround Sound Speakers

6 Analog TV Versus Digital TV Analog (Conventional) TV is on its way out. Digital TV is on its way in. The two technologies are not compatible. They will coexist for a while. How long will the change over take? The change is inevitable.

7 TV Display Technologies Direct View Projection

8 Direct-View Alternatives CRT Plasma LCD

9 Projection TV Alternatives Rear Projection Front Projection

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11 Cyan Magenta

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14 Deflection Yoke

15 Progressive Scan

16 Interlaced Scan

17 Creating Light on Demand Television pictures are drawn with light. When a electron falls from a high energy state to a low energy state, it gives up the extra energy as photons of light (visible and otherwise).

18 Nucleus Electron

19 Triads

20 Electron Guns Shadow Mask Phosphor Screen N S Purity Magnets

21 Poor Convergence Poor Convergence Poor Convergence

22 Characteristics of the CRT Crisper, more vibrant images than plasma or LCD panels. Most economical in sizes up to about 36 inches. Heavier, bulkier, and thicker than plasma or LCD panel.

23 Flat Panel Displays Plasma Liquid Crystal Display (LCD)

24 Plasma Display A phosphor screen is excited with UV light to produce visible red, green, and blue light. The UV light comes from tiny fluorescent-light pixels – one for each phosphor dot.

25 Front Glass MgO Rear Glass Dielectric Layer Plasma Cell Construction

26 Front Glass MgO Rear Glass Address Electrode Display Electrode Dielectric Layer Pixel Construction (Continued)

27 Front Glass MgO Rear Glass Address Electrode Display Electrode Dielectric Layer Phosphor Inert Gas Add Plasma and Phosphor.

28 uv Rear Glass Front Glass Green Cell

29 uv Rear Glass Front Glass Blue Cell

30 uv Rear Glass Front Glass Red Cell

31 Front Glass Rear Glass

32 Liquid Crystal Display (LCD) Works by blocking or passing light through a back lit screen. A liquid crystal is used to twist the polarization of light. The twist can be controlled by an applied voltage. Changing the voltage to the liquid crystal changes the polarization of light controlling how much light passes through two polarized filters.

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34 Polarizing Filter

35 Polarizing Filters Blocking Light

36 Liquid crystal can twist the polarization of the light

37 The twist can be turned on and off with a voltage. + -

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42 LCD Versus Plasma Plasma is brighter. Plasma can be viewed from an angle. Plasma comes in larger screen sizes. Plasma responds better to motion.

43 LCD Versus Plasma LCD panels come in a greater variety of sizes, especially below 40 inches. LCD panels use lower voltages and currents. LCD panels use simpler circuits. LCD panels have a longer life expectancy. LCD panels are quickly closing the gap.

Residential Audio & Video Systems Copyright © 2005 Heathkit Company, Inc. All Rights Reserved End