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DLP5500: Could we use 'off state enery' axis as a 'projection axis'?

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Replies: 5

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Part Number: DLP5500

Hello,

I am designing an optical system with DLP 5500.

Due to the lack of space, it would be better for me to put the 'projection axis' on the 'off state energy axis'. In other words, i would like to convert the 'off state energy' and 'on state energy' 

Would it be possible? 

Best regards, 

  • Hi rex,

    Depending on your optical design, this may work, but there is an important challenge that you should be aware of. Around the edge of the DMD is, what we call, a Pond of Mirrors (or POM). The POM is made up of several rows of mirrors permanently fixed in the "off" state.

    Therefore, if you are using the "off state energy axis," there will be a boarder of "on state" mirrors on the edge of your image. This post has a picture of what you might expect to see. Also, the block clear command only works toward the off direction.


    Best regards,

    Trevor

  • In reply to Trevor Dowd:

    Thank you Trevor for your reply, 

    However, i do not understand why there will be such a thing even though there is a flat-state-energy section between 'on' and 'off' stat, which separate them enough.

    Could you explain me why the boarder of 'on state' might be on the image(off state)???

    Thank you in advance,

    Rex,

  • In reply to rex KIM:

    Hello Rex,

    DMDs are designed with a border of non-addressable mirrors that are in the "off" state in typical operation.  This is by design so that the active array image appears to float in a dark background.

    This is so that if there is any illumination overfill (and there is always some overfill) it will not show up in the projected image.

    What is your illumination angle and desired projection angle (relative to the DMD normal)?

    Fizix

  • In reply to Fizix:

    Hello Fizix,
    I appreciate your help.
    What i am thinking of doing is just putting the light source at the typical place and change the places of projected image lens and projection lens(cf, 'DLP system Optics Diagram on www.ti.com/.../DLP5500 respectively so that i have 72 degrees(24+24+24) between the image lens module and the light source module.
    (In traditional mode, we will only have 24 degree between projection lens and lig ht source and this 24 degrees are not enough for me to place the two module one next to the another because of the thickness of the modules)
    (sorry for my bad dessin)
    I'am looking forward to having your reply.

    thank you in advance,

  • In reply to rex KIM:

    Hello again Rex,

    What you propose is doable, but you will have a bright border since the Pond of Mirrors (POM) pixels on the boundary will always be pointed toward your projection screen.

    You could create your own "off" border inside the fixed POM "on" border and make sure that your overfill is confined to the border you define.  This will mean of course that you will not be able to exactly use the full resolution.

    Are you needing more separation between the illumination and the projection?

    Fizix

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