DLPC350: Discontinuous intensity from DMD device in pattern sequence mode

Danilo A.

Part Number: DLPC350
Other Parts Discussed in Thread: DLP4500,

Hi Team,

We would like to ask your help regarding our customer's inquiry below.

I am using a projector that uses a DLPC350 chip to control a DLP4500 0.45 WXGA DMD device. I use the LightCrafter 4500 GUI 4.4.1 software to place the DMD device in pattern sequence mode with the Video Port as the image source. However, when I vary the grayscale of the the projected image, the grayscale-intensity relationship is linear until 50% gray (RGB 128) at which point there is a severe discontinuity where the projector intensity drops significantly. See attached image.

I am working on a project that requires the continuous modulation of individual pixel intensities. How can I access the full intensity spectrum while using pattern sequence mode?

Regards,

Danilo

over 2 years ago

0 Austin Snyder over 2 years ago

TI__Genius 12575 points

Hi Danilo,

Welcome back to the E2E forum!

To confirm, this is on a custom board?

Our team will need some time to look into this query. Please expect a couple of days for a reply.

Regards,

Austin

0 Danilo A. over 2 years ago in reply to Austin Snyder

TI__Mastermind 24705 points

Hi Austin,

Our customer confirmed that they are using PRO4500 from Wintech which contains DLPC350 controller. The module is available in the link below.

https://www.wintechdigital.com/PRO4500

Regards,

Danilo

0 Mayank Khandelwal over 2 years ago in reply to Danilo A.

TI__Genius 9971 points

Danilo,

We will try to reproduce this behavior on LCR4500 EVM and will let you know our findings.

Regards,

Mayank

0 Akhil Guntumadugu over 2 years ago in reply to Danilo A.

TI__Expert 3425 points

Hi Danilo,

Try refering to the e2e thread: LCR4500_EVM_Non_Linearity thread

Also could you share the .ini file to analayze and reproduce the isue on our side.

Thanks,

Akhil

0 Danilo A. over 2 years ago in reply to Akhil Guntumadugu

TI__Mastermind 24705 points

Hi Akhil,

We have received this feedback from our customer,

Below is the ini file I was using. But I think I may have found a solution. If I navigate to the "Image/Firmware" tab then within that navigate to the "Firmware Build" tab, there is an option for RGB color or monochrome. If I switch from RGB to monochrome only and then check "Use blue channel only" it seems to fix the issue. Previously when I would validate a sequence, I would get the warning "Black vector missing." I no longer get that warning. I am not sure why video mode always works fine even though I never adjusted the RGB vs monochrome setting before.

PatternSequenceSettings.ini

Regards,

Danilo

0 Cody Smith over 2 years ago in reply to Danilo A.

TI__Expert 3360 points

Hi Danilo,

Thank you for this update. We will look further into this and get back to you soon.

Thank you,

Chris

0 Akhil Guntumadugu over 2 years ago in reply to Danilo A.

TI__Expert 3425 points

Hi Danilo,

In Pattern sequence some dark time is to be set between each color(RGB) display pattern to ensure that there aren't image artifacts or discontinuity in the image quality. So care should be taken for the dark time placements in the pattern and also the LED edge delays to be calibrated properly.

In monochrome since there is only one LED source pattern the placement of dark time only impacts brightness.

In video mode the internal default pattern sequence with proper dark times will be used. Hence if the LED drive current levels are set properly you should see a proper linearity

Regards,

Akhil

0 Danilo A. over 2 years ago in reply to Akhil Guntumadugu

TI__Mastermind 24705 points

Hi Akhil,

Thank you very much for this information.

Regards,

Danilo

DLP®︎ products

DLP products forum

DLPC350: Discontinuous intensity from DMD device in pattern sequence mode