27

DLP4710

www.ti.com

DLPS125 – NOVEMBER 2018

Product Folder Links: DLP4710

Submit Documentation Feedback

Copyright © 2018, Texas Instruments Incorporated

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

•

All points below this curve represent higher usable life (and the further away from the curve, the higher the

usable life).

In practice, this curve specifies the Maximum Operating DMD Temperature that the DMD should be operated at

for a given long-term average Landed Duty Cycle.

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

During a given period of time, the nominal landed duty cycle of a given pixel is determined by 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 very close to a 100/0 landed duty cycle during that time period. Likewise, when displaying pure-

black, the pixel will experience very close to 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 1.

Table 1. Grayscale Value and

Landed Duty Cycle

Grayscale

Value

Nominal 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 2.

Table 2. Example Landed Duty Cycle for Full-Color

Pixels

Red Cycle

Percentage

Green Cycle

Percentage

Blue Cycle

Percentage

50%

20%

30%