• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 1 answer
  • Subscribers 29 subscribers
  • Views 1854 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Dew point of DMD

Nobuyoshi Arai44
Expert 2575 points
Other Parts Discussed in Thread: DLP3010

Hello DLP Pico team,

I would like to know about the Dew point of the DMD. There are some specifications in the DLP3010 datasheet. I am not familiar with this spec. Would you please explain what the dew point is?

It seems that the Dew point is a parameter of temperature when the dew condensation happens based on some temperature and humidity.

Does this temperature mean a case temperature or ambient temperature?
When the temperature becomes this dew point value, where can we see the dew condensation? Is this an inside or outside of the DMD (on the glass or on the DMD)?

Best Regards,

Nobuyoshi Arai

  • 0
    TI__Prodigy 720 points
    Arai San,
    Thanks for your question. We are gathering more information and will get back to you shortly.
    RegardsAnshul
  • 0
    TI__Genius 10495 points
    Hello Arai-San,
    Sorry for the late response. I hope following explanation will answer all your questions and make the dew point more understandable.
    It is true that dew point indicates the temperature at which the water vapor contained in the (ambient) air would condense. But “condensation” is not the reason we specify the dew point (since the DMD is both an electrical device and an optical device, condensation is a condition that should be avoided).
    Besides indicating when condensation will occur, dew point also provides a convenient means of indicating the amount of water vapor present in the local environment (air). It is for this reason that we specify the dew point. By adhering to the dew point limits specified in the Storage Conditions and Recommended Operating sections, the DMD will operate as it was intended. (Note: The dew point specification in the Absolute Maximum table is intended for accelerated stress testing only. The Absolute Maximum specifications do not apply to the normal operation of the DMD).
    The temperature refers to the case temperature and the condensation can be seen initial on the outside of the DMD.
    Best regards,Nadine
  • 0 in reply to Nadine Estermann
    Expert 2575 points

    Nadine-san,

     

    Thank you for the answer.

     

    I think your comment is answering the questions. But these questions were asked by our customer. After I answered to customer, if they do not have additional question, I would like to press “verify answer”. So, please wait for a while.

     

    Best Regards,

    Nobuyoshi Arai

  • 0 in reply to Nobuyoshi Arai44
    Expert 2575 points

    Hello Nadine-san,

     

    I got an additional question. Please let me ask one more question.

     

    As a Dew Point, it looks a maximum temperature is defined. Please let me check about this definition.

    In order to follow this specification, they should use the device so that the temperature is not less than the dew point value. Is this understanding correct?

     

    For example, when Humidity is 100% and Ambient Temperature is 24 degree, they should use the DMD so that DMD temperature cannot be less than 24 degree. Would you tell us whether this recognition is correct or not.

     

    Best Regards,

     

    Nobuyoshi Arai

  • 0 in reply to Nobuyoshi Arai44
    TI__Genius 10495 points

    Hello Arai-san,

    Thank you for your thoughtful questions.

    Yes, you will meet the specification with a dew point at 24C and an ambient temperature of 24C. Temperatures below 24C will create condesation on the DMD which has to be avoided.

    Even with an ambient temperature of 24C and a dew point of 24C there is still a possibility of condensation on the DMD. Therefore I would recommend to ensure a higher ambient temperature as 24C in your example to surely avoid any condensation on the DMD.

    You also should be aware that the ambient temperature might not be the same as the local ambient temperature which means the temperature in your product.

    For example, you can have an ambient temperature of 24C in your surrounding. Your product which contains the DMD has a cooling system like a fan which causes a local temperature below 24C at the DMD. With a dew point of 24C, you will have condensation on the DMD. In this case you should seal the DMD to protect against moisture.

    I hope this is understandable. Please let me know if you have any further questions.

    Best regards,

    Nadine

     

     

  • 0 in reply to Nadine Estermann
    Expert 2575 points

    Nadine-san,

    Thank you for the comment.

    I am sorry but I still do not know whether my understanding and your answer are correct or not.
    So, may I ask a question to confirm it again?

    According to your answer, the temperature should be higher than a dew point. But in the case of recommended operating condition, it is written that Long-term dew point is 24C and Short-term dew point is 28C. It looks the higher temperature is severer condition. Would you please tell us how I can explain about this?

    I also would like to know what temperature you are specifying in the datasheet. Is this an ambient temperature or a DMD temperature or other? There is no description like Tdmd or Twindow in the Long-term dew point and Short-term dew point in the page 8 of DLP3010 Datasheet. That is why I would like to know what temperature is defined.

    It would be helpful if you provide any comment.

    Best Regards,

    Nobuyoshi Arai / Macnica