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  • TI Thinks Resolved

Contrast Ratio

Intellectual 1680 points

Replies: 4

Views: 114

Hi E2E,

Good day.

Our customer would like to know the comparison of contrast ratio between all our DLP chipsets, do we have this information?

Thank you in advance for your help.

Regards,
Carlo

  • Hello Carlo,

    Thank you for using our E2E DLP forums.

    I would like to refer you to an existing post that talks on the subject of the native contrast for the DLP chipsets.

    https://e2e.ti.com/support/dlp/f/94/p/741240/2742862#2742862

    To summarize, there is no spec contrast that we state in our datasheet as there are many variables that can affect a system's contrast.
    Is your customer trying to hit a target contrast ratio?

    Regards,
    Oscar

  • In reply to Oscar Guevara:

    Hi Oscar,

    I want to use a digital micro-mirror array to selectively illuminate an area. In order to do this, I need to find the dlp chip that has the largest brightness ratio between “on” and “off”. I understand that the final contrast ratio is affected by many factors, but this difference in brightness is the most important factor in my project. 

    Is there another specification that you could recommend that might give me information about the difference in brightness between on and off states? Otherwise, it is very hard to know which dlp chip I should purchase.

    Thanks,
    Nigel

  • In reply to Nigel Clarke:

    Nigel,

    Contrast cannot be easily defined for just a DMD without an optical system.
    This is because at a high level, light that enters a DMD is also reflected off. Only an optical system can define the ON/OFF conditions that would result in the final contrast ratio.

    Reiterating what I have already stated, there are so many factors that affect the contrast ratio that we cannot give a spec for it.
    Here is an appnote that gives further information on contrast ratio in terms of efficiency. (DMD Optical Efficiency for Visible Wavelengths).

    Regards,
    Oscar

  • In reply to Oscar Guevara:

    Thanks Oscar,

    The app note about optical efficiency was very helpful. Is there a similar app not that discusses scattering and/or the ability for the projector to block light when it's set to the off state?

    I see what you're saying about the contrast ratio.  If I can better define the system, would there be a way to the contrast ratios?

    For example, let's say there is a collimated light source with an aperture equal to the diameter of the DMD. The light reflects off the DMD into another aperture of equal diameter.  Both apertures are 2 inches from the DMD. What is the ratio between the intensity of light when the DMD is set to an on and off positions?

    If you have it, would also be helpful to see information about the angular distribution of scattered light in the ON and OFF states

    Nigel

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