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DLPC3479: Discontinuous gray level change between 127 and 128

user534742
Prodigy 175 points
Part Number: DLPC3479
Other Parts Discussed in Thread: DLP4710

Hello TI Exprets,

We are testing the gray scale accuracy of DLP4710 and found that there is a discontinuously of brightness level between gray 127 and 128.

In our experiment, the brightness of gray 128 seems to be equal to brightness of gray 122.

Testing conditon is 8bit mono internal pattern mode and we are using our designed board. 

Please give us any advice.

Thank you.

  • 0
    TI__Genius 10925 points

    Hi User, 

    Welcome to TI E2E Forums! One of our experts will look into your query and respond soon.

    Thanks & Regards,

    Hirak.

  • 0 in reply to Hirak Biswas
    TI__Expert 4610 points

    Hi User,

    Can you share the lumens number details for your different gray level. I am not seeing the same brightness for gray-122 and gray-128 on my hardware.

    Also can you share the .bmp file you are creating for your gray 8 bit pattern.

    As you mentioned it is your design, did you follow the same design as our reference EVM design? 

    Also... if possible can you check the same with white color ramp pattern (available in GUI - Display -> Pattern and images). Are you seeing the brightness jump in the color ramp pattern or a smooth ramp pattern ?

    Thanks,

    Navneet

  • 0 in reply to Navneet Singh
    Prodigy 175 points

    Hello Navneet,

    Thank you for your reply.

    I have tested same thing on EVM, and the result seems to be same.

    I will insert 3 files.

    1) 1D Ramp image

    2) Exposure condition on EVM

    3) Captured image of ramp pattern on screen

    You can see gray level discontinuity indicated with arrow on 3rd image.


  • 0 in reply to user534742
    TI__Expert 4610 points

    Hi User,

    let me try the same timings as yours on my hardware. I will get back to you with my findings very soon.

    Thanks,

    Navneet

  • 0 in reply to Navneet Singh
    TI__Expert 4610 points

    Hi User,

    I can reproduce the issue as above mentioned. We are working on this to find the root cause and will fix this in next maintenance release. 

    I am sending you the friend request and I will inform you whenever we are ready with the next maintenance release of this fix.

    Thanks,

    Navneet

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