DLP9500: The image of the data loaded before the reset appears faded

Part Number: DLP9500
Other Parts Discussed in Thread: DLPC410, DLPC910

Tool/software:

Hello,

I am using an FPGA to control the DLPC410 and DLP9500 at high speed.

I want to continue exposing while loading the next image data, but when I ran it at a slow speed to check, I found that the image of the next data loaded was faintly visible in the current image on the DMD.

So, I have some questions :

- Will the loaded data change the mirror angle even if it is not reset?

- If the mirror angle is changing, how long does it take from loading the data until it affects the mirror angle? (50us or more is fine for our purposes.)

- We are planning to develop a product using DLP9500X and DLPC910. Does the same phenomenon occur with DLP9500X?

Current Image before loading next image data. (block 4-9 mirror on, other block mirror off)

Current image after loading next image data.

Next image.

Thanks,

Tanaka

  • Hello Tanaka-san,

    When new data is loaded the pixels that will change value (i.e. 1 to 0 or 0 to 1) do experience a very small change in the landed angle of those mirrors as the CMOS cells under them change state.

    It is very easy to see in the way that you have taken the pictures, because at that distance the camera effectively presents a very small aperture and you can easily see the subtle changes.  Typically optical systems are designed such that this does not show up in the output image.  Please see section 8.5 of the DLP9500 data sheet that discusses some of the optical issues.

    Fizix

  • Hi, Fizix,

    Would it be possible to provide an estimate of roughly how many degrees the slight angle change is?

    In our device, the incident light on the DMD has a certain angular spread, and depending on the extent of the DMD's angle change, the amount of reflected light passing through the aperture in the optical system may decrease. This raises concerns that pixels with angle changes and pixels without changes will result in uneven exposure on the target.

  • Hello again Tanaka-san,

    The change in angle is on the order of around 0.2 degrees.  How small is the Numerical Aperture in your system.  If the source is small an output aperture that is slightly bigger should capture the light.  

    Fizix

  • Hello, Fizix,

    Thank you for your answer.
    It was good to know that the angle change is sufficiently small. A change of about 0.2 degrees would not be a problem in our device.

    Tanaka

  • Tanaka-san,

    You are welcome.

    Fizix