LCD vs. DLP

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LCD vs. DLP
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How does DLP work?

• DLP is a reflective technology.
• Filtered Light is reflected by DMD either toward
  or away from the lens
• Rapid sequential RGB images are perceived by eye
  as full colour.
• Brightness and Colour saturation influenced by
  colour wheel

Single Chip DLP Optical Engine
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How Does LCD Work ?

• LCD is a trans-missive technology.
• Filtered light can pass through Red, Green Blue
  LCD panels where pixels are open.
• A full colour image is created in the prism and
  projected through the lens.
• Full colour is always an RGB compound

An LCD Optical Engine
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DLP or LCD Any Advantage?
What is the impact on Image Quality?

• Brightness
• Colour Reproduction
• Contrast
• Grey Scales
• Image Resolution Sharpness

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Image Brightness

• Full Colour consists of an RGB Compound
• In LCD, RGB compounds are continuously projected
• Result is improved optical efficiency
  consistently bright images

Mechanism of color reproduction 3LCD
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Image Brightness

• In Single Chip DLP, RGB signals are projected
  sequentially
• When Red is displayed Green and Blue are
  effectively filtered out
• Result is reduced optical efficiency and lower
  brightness.

Mechanism of color reproduction Single Chip DLP
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Colour Reproduction
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Colour Reproduction

• In single chip DLP, the sequential projection of
  white to increase brightness, reduces colour
  saturation and limits colour reproduction.

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Colour Reproduction

• By far the biggest problem with single chip DLP
  is the Rainbow Effect.
• As a result of the way in which the image is
  generated a separation of colours may be visible.

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Contrast

• Contrast ratio defines the relationship between a
  displays the whitest white, and blackest black.
• Published contrast ratio refers to full on/off
  contrast
• DLP projectors quote a higher on/off contrast
  ratio than LCD projectors
• Why?
• Is this Significant ?

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Contrast

• Actual contrast is significantly reduced in
  normal ambient light conditions.
• A higher on/off contrast level delivers limited
  on screen benefit.

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Grey Scales
LCD
DLP cant display gray scales smoothly because
DMD is controlled by on-off and on-time.
DMD
Dithering method is used in order to compensate
poor gradation in digital controlled device.
Gray scale compensation
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Image Resolution Sharpness

• Both LCD and DLP are capable of resolving images
  at the same resolution.

• With LCD the inter-pixel gap caused by the
  panels structure can be visible.

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Image Resolution Sharpness

• With single chip DLP, the data images can lack
  sharpness.
• This is because the edge definition of each pixel
  mirror is softer and less well defined than LCD.