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Micromirror Landed-On/Landed-Off Duty Cycle (continued)

7.7.4 Estimating the Long-Term Average Landed Duty Cycle of a Product or Application

During a given period of time, the Landed Duty Cycle of a given pixel follows from the image content being

displayed by that pixel.

For example, in the simplest case, when displaying pure-white on a given pixel for a given time period, that pixel

will experience a 100/0 Landed Duty Cycle during that time period. Likewise, when displaying pure-black, the

pixel will experience a 0/100 Landed Duty Cycle.

Between the two extremes (ignoring for the moment color and any image processing that may be applied to an

incoming image), the Landed Duty Cycle tracks one-to-one with the gray scale value, as shown in Table 2.

Table 2. Grayscale Value and

Landed Duty Cycle

Grayscale Value

Landed Duty

Cycle

0%

0/100

10%

10/90

20%

20/80

30%

30/70

40%

40/60

50%

50/50

60%

60/40

70%

70/30

80%

80/20

90%

90/10

100%

100/0

Accounting for color rendition (but still ignoring image processing) requires knowing both the color intensity (from

0% to 100%) for each constituent primary color (red, green, and/or blue) for the given pixel as well as the color

cycle time for each primary color, where “color cycle time” is the total percentage of the frame time that a given

primary must be displayed in order to achieve the desired white point.

During a given period of time, the landed duty cycle of a given pixel can be calculated as follows:

Landed Duty Cycle = (Red_Cycle_% × Red_Scale_Value) + (Green_Cycle_% × Green_Scale_Value) + (Blue_Cycle_% ×

Blue_Scale_Value)

where

•

Red_Cycle_%, Green_Cycle_%, and Blue_Cycle_% represent the percentage of the frame time that Red, Green,

and Blue are displayed (respectively) to achieve the desired white point.

(4)

For example, assume that the red, green and blue color cycle times are 50%, 20%, and 30% respectively (in

order to achieve the desired white point), then the Landed Duty Cycle for various combinations of red, green,

blue color intensities would be as shown in Table 3.