Latitude e6420 - Disable automatic brightness?

Hey guys, I'm still getting used to the new laptop, and I have found a problem which I can't seem to find the answer to...

When the screen is dimmed - that is, almost all the way down, it seems that there is a random, noticeable, shift in brightness every once in a while. It seems like it's less shift than normal Windows automatic dimming, so I'm tempted to blame an Automatic Brightness sensor... problem is, I see no indication that this unit has such a unit (on older Dells, there was a "camera" looking lens on the bottom bezel). Also, neither in the BIOS nor in the system control panel is there any option to vary this. Thoughts?

Bonus Question: Any idea how to enable the fingerprint reader?

 

Ummm... so the Dell ProSupport guy had no idea. He looked at the manuals, etc., and it turns out they pulled it from the BIOS and it's not in the Dell Control Software either... there is an option to make a hotkey to control it, but the hotkey doesn't appear to do anything. Is there some generic way to tell Windows *not* to use ALS data?

 

I believe that I have found the solution... I went the Windows route. I was trying to catch what the hotkey did using regmon (or whatever they're calling it now) and, on a whim, I searched the Registry for "Brightness". Sure enough, I found a reference to a service that controlled it (it's probably standard with Windows, but I've never looked before). It's now set to 'Disabled' so that the power manager can't go turning it back on again

 

Errr, AFAIK there is no ALS on the E6420, unless they're using the webcam.

I have my webcam disabled but I don't have that issue, so not really sure if the two have anything to do with each other. Unless there is some dynamic contrast setting that's enabled somewhere?

 

I have no idea... the problem was only noticeable on 'Maximum Battery' power mode... the Dell rep confirmed that it was supposed to have ALS, though it may have been an *option* that was never really put on... we were both surprised that it would be on there with no BIOS level control or even Control Point software. The precise symptom:

Screen is full dim (default for that power plan) - open up a PDF w/white background and about a second later the screen dims. Flip back and the screen brightens. Occasionally it seemed to flick back/forth which is why I was thinking ALS. However, on the old latitudes there was a little 'seeing eye' thing for ALS on the bottom bezel for the screen.

 

Scratch all that... it was Intel DPST, hence it only showed up on battery and on power saving modes (where Optimus kept Intel HD 3000 on all the time). Disabled it and it seems actually improved.

 

Jacob,

I know this thread is a little older, but I found it via search - I am having the exact same issue on my new Dell Latitude E6420. It sounds like exactly what you described. Can you provide some details on what you mean by Intel DPST and how that could be disabled? Did that fix the issue for you?

My screen changes brightness (fairly slightly) depending on what is on the screen, but only when on battery power. This is a new computer and issue for me, and it's driving me batty!

Thanks!

 

Yes, I haven't had any troubles since I disabled it. The reason it was hard to pin down was it only applies when Optimus decides to use the Intel Video card. There is no such problem when it's in a high performance mode and the NVidia chip is always on. If your power settings are using Intel, right clicking on the Desktop you should see something about managing Intel settings. I don't have it at the moment but I'm in Ultra Performance mode... I'll have to see if I can get into it some other way. Try:
Graphics — How to open the Intel® Graphics Properties window

If you can get in there, just have a peak under the "Power" tab, and you should see "Display Power Savings Technology"... just uncheck this. That's what I did, though I can't walk you through it at the moment.

 

HELP! I can't adjust the brightness its too bright.I have a DELL Latitude E6420 too and need step by step of how to do it.It doesnt give me the option anywhere and not even hot keys work

 

drives me batty sometimes also, esp because the laptop can ignore "control panel -> Display -> Adjust brightness (power plan) -> change plan settings -> advanced settings -> display -> enable adaptive brightness -> disable"!

On my E6500, I have the Fn key that will allow brightness adjust with the up/down keys. There is also the Fn-left key "Auto"!!! key. Try that -- it worked for me. I must be accidentally hitting that key when adjusting brightness sometimes, which then sends my auto-adjust into drive-me-crazy mode again.