Digital Light Processing

1. PROJECTION SYSTEMS AND
INTERFACING
• Presented by
VARUN K
varunkpa@gmail.com

2. PROJECTION SYSTEM
Definition:
• A Projection system is an optical device that projects an image or
moving images onto a surface or a projection screen.
 First idea of projecting an image came in 1420.
 The first projector called the Magic Lantern was developed in 1650
 Types:
1.CRT
2.LCD
3.DLP

3. CRT PROJECTOR
• projector which cathode ray tube as the image generating
element. Image is focused and enlarged to a screen using lens
kept in front of CRT
• Usage of 3 CRT system-lenses to obtain color images.
• Specifications
A. CRT size
B. Scan rates & HDTV
C. Max.Resolution
D. Input
E. Focus
F. Peak lumens

4. SPECIFICATIONS
• Peak lumens: Amount of energy that coming from CRT.
Entry level projector:600-800 lumens
intermediate level projector:1000-1200 Lumens
high performance CRT:1200+ Lumens
• CRT size: Measurement is taken from corner to corner
on the front of the tube face.std size:7”,8”9”.
• Scan rate &HDTV: Ability to display HD videos depends
scanning ability. Expressed in no of scanning lines.
HDTV: Requires a scanning rate of 33.75 KHz and 50Mhz BW
due to line doubling feature.

5. SPECIFICATIONS(Cont..)
HDTV:NTSC-standard contains 525 lines that makes up the TV
image.(Scanning rate 15.15 KHz).HDTV introduces additional
scanning between line. -31.5Khz(520p).
line triplers,Qudraplers:48k,64k
High grade projectors(CAD):135 kHz
 Max Resolution: Maximum resolution that a projector can
accept-depends tube size& Quality of internal circuitry.
High resolution: Individual scan lines are close enough-Over
resolution –Overlapping softening.
Low resolution: scan lines are visible
fixed size-Proper resolution=> 7” 480p ,8” 720p. 9” 960p

6. SPECIFICATIONS(Cont..)
• Input: Different video standard signal that we can give
I. Composite video:
lowest quality but common.
limited to 480p
HD impossible
2. S Video:
Limited to 480p
B,W, Colors are send different medium
25% picture details more than Composite.
3. Component/YPBR
480-1080support
videos from HD cable/satliite box 720p/1080p from HD DVD

7. LCD PROJECTOR
• Components: LCD panels
Prism
filters to create image on screen
• The lamp gives white light that passes through a polarizing
filter .Polarizer accepts light travelling in same plane. Other
lights are blocked.
• Then Light passes through series of dichroic mirrors
.separation of light in to RGB
• 3 colors are sent to separate LCD panel each is capable of
controlling one color. From this light is combined using prism
and send out to the LCD projector.

8. LCD

9. SPECIFICATIONS
• Brightness: It is the quality of the state being bright.
Unit:Lumens
• Contrast Ratio: Ratio of Luminance of brightest color to that
of darkest color that the system is capable of producing.
• Resolution: Resolving capacity. People who needs Wild screen
usually takes 16:9 format.3 standard resolution.
1024*576,854*480,1280*720.
• Projector with resolution854*480 ,input=480p works well.
Projector with resolution1024*576 ,input=480p will not
works well. Projector has to distribute 480line information in
576 lines=> image become softer. So there should be
compatibility

10. SPECIFICATIONS(CONTD…)
• Uniformity: Consistency of brightness over the entire image.
90%=>It is projecting a pure white image on the entire
screen, there will be no more than 10% variation in intensity
across the entire screen. %uniformity α accuracy.
• Image size, Throw distance: Max and min size of the image
that the projector is capable of projecting. The maximum and
minimum distance with in which projector will focus.
• Zoom Ratio: This refers to the amount of difference between
the smallest image size and the largest, without moving the
projector. A typical projector has a zoom ratio of 1:1.3. This
means that if the smallest image for a given screen distance is
10 feet, the largest will be 13 feet.

11. SPECIFICATIONS(Cont..)
• Throw Ratio: This is tied to the Zoom Ratio. It tells you the
minimum and maximum distance the projector can be from a
given size screen. For example, a projector with a Throw ratio
of 1.7 - 2.2 can fill a 10 foot screen when placed between 17
feet and 22 feet from the screen.
• Scanning Frequency: Different computer outputs have
different vertical and horizontal scanning frequencies. For
example VGA (640 x 480 resolution) can be as low as 32 Hz
Horizontal and 60 Hz Vertical, and SXGA can be up to 81 Hz
Horizontal and 76 Hz Vertical.

12. SPECIFICATIONS(Cont..)
• dB Rating: This refers to the amount of fan noise the projector
produces. A lower number means that the projector is
quieter. Since every 3 dB is a doubling of sound, a projector
with a rating of 36 dB is twice as noisy as one with a rating of
33 dB.

13. DLP PROJECTION SYSTEM
• Based DLP technology introduced in 1997.
• DLP technology: Introduced by Dr Hornbeck of TI
• Used in DLP front end projectors, DLP rear projection TV sets .
• DMMD: Image is created by microscopically using small
mirrors in matrix on semiconductor chip called digital
micrometer device
• 16um thickness-each mirror represents each pixel.
• No of mirrors corresponds to resolution.
• 2 types :Single chip DLP
Three chip DLP

14. DIGITAL MICROMETER DEVICE

15. INTRODUCTION-DMD
• Optical semiconductor which is the core of the DLP
technology
• Several hundred microscopic mirrors arranged in a
rectangular array, each mirror is one pixel.
• Aluminum alloy mirrors, silicon based electrostatic
drives, silicon microelectronic
• 1280*1042 DMD
• Central reflective sections have 1310720 tiny mirrors,
Over this glass is sealed
• Mirror size=16um.

16. DMD structure
• Integrated MEMS which is fabricated on cmos RAM
cell.
• Mirror(Alumina)-connected to underlying yoke-yoke
connected to hinges supported by post that is
attached to underlying structure.(Memory cell
beneath the post).
• Electrostatic field between memory cell and yoke
generates electrostatic torque.
• Torque produces mirror rotation in +/-

17. DMD

18. Operation of single mirror
• The mirror is on the yoke that can rotate on two
torsion hinges.
• Yoke connected to yoke addressing electrode.
• Which electrode is energized depends up on thee
status of the memory cell beneath it.
• ‘1’in the cell-mirror moves +10 deg.
• ‘0’in the cell-mirror moves -10 deg.
• Each cell is made of SRAM

19. SRAM cell write ‘1’

20. SRAM
• Bit lines charged to 2.5v
• Choose w=1;
• Apply b=1 and b’=0;
• Vb=+5 and Vb’=0
• Vy rises to +5v and Vy fall to 0
• Recharged to +2.5 v

21. How to control mirror movement
• Wheel rotation speed:60Hz
60rev/sec 180color changes/sec
• 1/180=5.56 msec to pass light source.
• Each mirror should be capable of moving less than
5.56
• Practical:20 usec
• So for any given color mirror of any pixel can move=
5.56*0.001/2usec=278 times
• 8 bits 256 pos

22. How intensity is projected
• Chip receives the video signal & separates to RGB.
• Each color component intensity is translated to a value
between 0 & and stored mirror control byte.
• Initial reset-latch bias current is turned on
‘1’  mirror deflect towards projection lens (+10)
‘ 0’ mirror deflect towards projection lens (-10)
No light, again neutral position ,Repeated for all bits
• To process single video frame each mirror will move 8 times
Brightest pixel  Each at +ve angle
darkest pixel  Each at -ve angle
• Remaining level combination of these orientations
• Cycle time of DMD , integration time of human eye
compatibility

23. How intensity is projected

24. NEC NP-V300WG DLP

25. NEC NP-V300WG DLP

26. ADVANTAGES
• Sealed imaging chip: Most DLP projectors have sealed DLP
chips that eliminate the possibility of a dust particle alighting
on the imaging plane, which could create a dust spot on the
projected image.
• Filter-free. DLP projectors that have sealed DLP chips can
operate without air filters. Thus maintenance is reduced since
there is no need to periodically clean or replace filters.
• No image persistence. If one displays a static image for an
extended period of time, an LCD projector with organic LCD
panels may have a tendency to retain a subtle ghost of that
image even after the subject matter is switched to another
image. This does not occur on a DLP projector.

27. VGA INTERFACE
• VGA: Display hardware introduced
by IBM.Amplitude modulated
computer display standard.
• A Video Graphics Array (VGA)
connector is a three-row 15-pin DE-
15 connector.
• DE-15 is also conventionally called
RGB connector
• VGA connectors and cables
carry analog component RGBHV
(red, green, blue, horizontal
sync, vertical sync) video signals,
and VESA Display Data
Channel (VESA DDC) data.
• The VGA interface is not
engineered to be hot pluggable.
although in practice this can be
done and usually does not cause
damage to the hardware or other
problems.

28. HDMI INTERFACE
• HDMI (High-Definition
Multimedia Interface)
• audio/video interface for
transferring uncompressed
video data and compressed or
uncompressed digital audio data
from an HDMI-compliant source
device.
• HDMI is a digital replacement
for analog video standards
• HDMI implements the EIA/CEA-
861 standards, which define
video formats and waveforms,
transport of compressed,
uncompressed, and LPCM audio,
auxiliary data.

29. HDMI(CONTD..)
• Several versions of HDMI have been developed and deployed
since initial release of the technology but all use the same
cable and connector.
• newer versions have optional advanced features such
as 3D, Ethernet data connection.
• The maximum pixel clock rate for HDMI 1.0 was 165 MHz,
which was sufficient to allow 1080p and WUXGA (1920×1200)