Screen Slightly Changes Color on Press.

[EtherealRemnant]

Well installing the Alltel ROM didn't do anything for me so consider yourselves lucky. *shrugs*

[phazed]

In order for this to make sense you will need to know some things that make an LCD operate, so bear with me.

A LCD (passive or active matrix) only change state when the software issues a screen update or refresh. For instance, if you press up and down on your home screen, the software will fill the Display Controller's Buffer to "update" the changes by the user.. in this case to reflect that you are highlighting your calendar, live search, the Start Menu, or whatever else you manipulate. Otherwise, if there have not been any changes on the screen.. the software doesn't keep refreshing the LCD... there is no need to waste battery and processor time in doing so. This is the basis for saving power because the screen communication can stop.

First is the Display Controller. The Display controller is a microprocessor that directly interfaces with the LCD physically in order to switch each individual pixel independently. This is (generally) integrated onto the Screen itself. The Display Controller has a ribbon cable that connects to the Qualcomm MSM7500's MDDI (Mobile Display Digital Interface). That is... the 400MHZ ARM-6 Main Processor essentially has a Video Card built into the same chip. Don't believe me? Check out this post: http://forum.ppcgeeks.com/showthread.php?t=7991 and you can verify visually the Qualcomm processor model. Then go to Qaulcomm...
Qualcomm MSM7500 Overview: http://www.cdmatech.com/products/msm...t_solution.jsp
Mobile Display Digital Interface (MDDI):
http://www.cdmatech.com/technologies/mddi.jsp

I have worked with a lot of LCD passive and active matrix screens (I'm an Electronics hobbyist for fun, and a Union Electrician for work) and I am 95% positive it is a software issue. It is definitely not because of a weak screen, and this is why...

When my ppc6800 is fully charged I don't have any problem with the screen changing colors.. it's only when its at around 30-40% that it starts to do this.

Also, I made a PowerPoint Presentation (http://forum.ppcgeeks.com/attachment...1&d=1192262056)with a white background and 7 frames with different letter. If I play this slide show and press buttons/tap the color shift doesn't occur. It seems the processor is not put into hibernate or power save while having animation. So it's not hardware.

But why does this happen?
This is because either:

1. The MDDI enters a Hibernation mode when the image isn't changing, saving battery power. When the MDDI is needed again it "wakes up" and causes this color change. This reinitialization re-connects the Processor to the Display Controller. There is a block of machine code that runs to do this.. and this is where the problem could be. It should be fairly simple for HTC to fix, as I know there isn't a problem with the LCD/Disp.Controller.

2. As power decreases the processor goes into power save mode, which will generally decrease the communication rate between the Display Controller and the MDDI. producing this effect. Again.. it's all programmed in there(ROM).. Maybe an option to turn this feature off or on at the expense of battery? Or fix the Low Level programming?


phaZed

[EtherealRemnant]

Considering that my battery hasn't hit that point but once so far (I've had it since Monday and have charged it twice - the first time and about 2 days ago) and it keeps happening all the time, I don't think its battery dependent.

[phazed]

Ya, but power features may kick in premature or incorrectly for the screen. Perhaps after May they started using a different screen manufacturer and never changed the software.

Try the PowerPoint presentation on there and run a Slide show. While the slide show is looping through if you tap or move the jog wheel do you see the screen changing colors? I didn't, which led me to believe that PowerPoint made an API call to keep the processor Active and out of power save/hibernate. Therefor if it works in PowerPoint correctly.. it can work anywhere correctly.

[SINNN]

Sorry phazed. But you might be correct but all that gets thrown out the window if HTC changed to a inferior screen like they have done here where I am at. My last 4 moguls screens are a joke compared to my first. How do I back this theory up? Simple... logic tells me. I can definite feel a physical differfence between my GF Mogul and my current mogul. Hers feels hard a rigid and does not dimple in a lot when you apply slight pressured with the stylus. Now.... if I apply the same pressure to my current mogul then it feels softer and dimples in a lot more. Very noticable. I had my GF feel it and tap it and she says yes its different. HTC so far says thru their reps that they don't know if the screen is different. huh....

[phazed]

SINNN:

I understand where your coming from. I tried to find out what screen they use (Maker/Model) but was unsuccessful. You got to understand that there are really two "screens" there is a clear touch panel that is overlayed on top of the LCD display... and simply touching the overlay *should* not have ANY effect on the screen redraw. In fact the touch overlay has a separate ribbon cable and connects directly to the Qualcomm CPU.. Therefor, any physical TAP you make doesn't directly affect the screen! Also, if it was a touch panel/screen problem.. it wouldn't make any sense that a Jog wheel or button press causes the same effect. That leads me to believe it has nothing to do with the physical screen, and has more to do with the low level machine code that produces changes to the screen.

Think of it like the Touch overlay is a keyboard on your Home computer.. the processor takes the input.. and decides what it needs to do.. then outputs it to the screen.

This is the order it works...

Touch Panel-->Qualcomm CPU-->Fill Display Controller Buffer with new frame-->Display Controller Produces per pixel changes

My screen is very hard.. and I can't feel or see ANY "sinking" into the screen when I press it. That was not the case with my 6700, so I know what you mean. And I also consider the "sinking" to be inferior in design.. but the electrical connections and sequence of events is still the same regardless.

BTW, most hardware changes are done because of:
Money - They found a cheaper supplier
Stock - A supplier could not produce the volume required
Technology - Perhaps a more efficient screen, or a different model screen is replacing another from the same manufacturer.

So it is very unlikely that any Tech at HTC will know about specific part changes.. most of the time only the Assembly line gets that heads up.

[SINNN]

Well sinced your knowledgable, how you do explain the yellow backlight? Clearly my GF mogul is 100 hologen whited, and mines is yellow and in no way white. This is plain and simple to me... they swapped for a cheaper screen. Now we the consumers with keen eyes get the shaft. I just wished I never turned in my first Mogul. It was soooo much better.

[SINNN]

Phazed. You seem to have good knowledge on electronics. Can you tell me if the backlight is part of the screen as one unit. Or is the backlight a seperate conponenet to the screen?

[EtherealRemnant]

phazed, your PowerPoint presentation exhibits the same behavior as any other app. Each roll of the scroller creates a different tint on the screen.