Fundamentals of Projection Technology_SIMULATION_updated_pptx

55 Pages·2014·4.28 MB·English

Fundamentals of Projection
Technology
Alen Koebel, Senior Design Qualification Specialist,
Christie Digital
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SIM University 2014
In This Seminar
• We will learn about projector technology by exploring some of the
essential inner components of digital projectors.
• We will discuss how video signals are processed by projectors with
an emphasis on the operations that are important for simulation.
• We will discuss how light is transformed into an image on a screen,
including a discussion of different kinds of light sources.
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in use today: LCD, LCoS and DLP.
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What’s Inside a Typical Projector?
Light Engine
w/ Micro-display Panels
Lens
Low-Voltage
Lens
Power Supply
Mount
(LVPS)
Frame
Fans
Light
Skins
Source
Light Source
Power Supply
Input Panel
Processing
Electronics
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Projector Functions
• A projector’s primary function is to input video signals in a variety
of formats and output a focused image onto a projection screen.
• In order to do this it has to perform a number of supporting
functions:
•
Turn on/off and regulate the brightness of a lamp or other light
source.
•
Focus the light in a uniform manner onto the micro-display panel(s),
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•
Accept and process video signals into red, green and blue
component images in the pixel format of the panel(s) and send them
to their respective panel(s) with defined timing.
•
Modulate the light hitting the panel(s) with the image data.
•
Combine the red, green and blue images and focus an enlarged
image onto a screen.
•
Accept commands for configuration and operation.
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Critical Specifications
• Image related
•
Pixel format (H x V)
•
Light output (brightness)
•
Contrast ratio (black level)
•
Color gamut
• Others
•
Power
•
Size, shape and weight
•
Appearance (Industrial design)
•
User interface
•
Projector environment
•
Reliability
•
Regulatory compliance
•
Cost
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Image Parameters
• Pixel format
•
Horizontal x Vertical pixels
•
Pixel aspect ratio (square or rectangular)
• ÷
Display aspect ratio (width height)
• Grayscale
•
Dynamic range: The range from black to white
• Brightness or luminosity (light level of peak white)
• Black level (light level of black)
÷
• Contrast ratio (brightness black level)
•
Resolution: How finely the range from black to white is divided
• Number of bits (digital) or signal-to-noise ratio
(analog)
•
Transfer curve, bits or voltage in to light out (“gamma”)
•
Color of white (“color temperature”)
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Image Parameters
• Color
•
Color space (e.g., RGB, YCbCr)
•
Co-ordinates of primary colors (defines the gamut)
• Display-dependent (only) parameters
• →
Resolution this is independent of the projector’s pixel
→
format could be lower!
•
Area uniformity (black and white, color)
•
Image refresh method (raster-scanned or other)
•
Refresh rate (At what rate are images redrawn?)
•
Duty cycle (ratio of On time to Off time during each
refresh)
•
Persistence (nature of image decay)
• And for moving images...
•
Update rate (How fast can the content change?)
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Video Processing
• Video signals need to
Video
be processed for output Front-end Back-end
input
processing processing
to the micro-display signals
panels.
• Processing can be
divided conceptually
into front-end and back-
end portions, which may
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circuit boards.
• All video input is
ultimately converted to
red, green and blue
image components for
display.
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Additive Color
• Every color a typical display produces is a combination (sum) of
red, green and blue light – the “primary” colors – in controlled
amounts. For example:
• Red + green = Yellow
• Red + blue = Magenta
• Blue + green = Cyan
• Equal parts Red + Green + Blue = White
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light by filtering a white light source (e.g., Xenon or UHP lamp).
• Newer light-source technologies for projectors (e.g., LED, laser)
can produce red, green and blue light directly.
• Some projectors also filter out (or directly produce) what are
normally considered “secondary” colors – cyan, yellow and
sometimes magenta for a five-color or six-color system – or add
other wavelengths of light such as infrared (IR).
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