Altering backlight brightness below default minimum

[PinkShinyRose]

I am new to windows 7, I used windows XP, but changed to linux just before windows 7 was released. I use a medion MD97888 laptop, with an intel chipset (and it was bought with an OEM version of windows 7). Now I want to use windows to view some DRMed silverlight videos from my university.

Due to my often nightly studying, sleep requirements and preference for a dimmed screen I am looking for a way to dim my laptops backlight from windows. In linux I use 'echo x > /sys/class/backlight/intel_backlight/brightness' to dim my backlight at night to the lowest possible level without turning it off (50 in my case). So I searched in duckduckgo and ixquick hoping to find something similar. I found several programs to dim the screen, but the only thing those programs actually seemed to do is to reduce the video brightness (without dimming the backlight), and most do not even dim tooltips and shellmenus.

There is a list of programs at http://www.makeuseof...efault-minimum/ the desktop lighter is the only one dimming tooltips (but it does not seem to dim the backlight, at least not to the extend that I am looking for).

Does anybody have a solution? Is there a setting in windows that is similar to the one I use in linux?

EDIT: I just realised I forgot to mention something: I tried using the hotkeys and the powersettings, but the lowest end of the slidebar is too high for my preference (I had the same problem in linux mint but solved that using the method described above).

[MANEMAN]

As you are using - 'echo x > /sys/class/backlight/intel_backlight/brightness' in Linux to acheive what you want there would seem to be no reason why it shouldn't work in Windows with similar code/command.

This would seem to suggest that the LED Backlighter Controller Board (BCB) is indeed programmable by the user which is suprising for such a low rated computer. It would seem from the command that you are giving that Intel is probably controlling the voltage input to the LED rails or switching out some rails. Measurement by you of any voltage change from the BCB whilst using Linux would confirm this.

I find that controlling LED Backlight voltage/settings through intel chipset or video settings a bit strange, as such settings are usually factory preset on low cost computers across a fair spectrum for the general public, but obviously if you have done it, - it must be so. Where did you come across such a command in the first place ? Is it perhaps just an "Easter Egg" found that is only available within Linux ?

Without a manual or circuit diagram these are the only suggestions I can come up with.

Contact Medion or Intel with your findings, they will have an answer for you. (Or perhaps the retailer Aldi ?)

John.

[PinkShinyRose]

Thank you for your reply, unfortunately I am not able to check the voltage on the backlight. The command I used on linux is mentioned on several (mostly ubuntu) forums. It is actually advised for a range of hardware, so maybe the feature is blocked in the intel drivers for windows (or is it not allowed by the kernel). The scale in which the backlight can be dimmed is discrete (with steps of 50).

Considering it works on my low end system, the limit could be imposed for user comfort. I have also read about some people having trouble with the limited dimming options when migrating from windows vista to 7 (or was it xp to vista?) which seems to be fixed to a certain extend when installing newer drivers (which does not work in my case, probably because win7 was preinstalled). Does this mean that dimming is limited beyond the limitations imposed by the preprogrammed capabilities of the firmware?

The backlight can be turned off (or dimmed completely?) using a preprogrammed hotkey. This complete absense of the blacklight does, however, differ from the regular dimming in that dimming to 0 can be undone using the normal dimming settings, but when the backlight is turned off the dimming settings have no effect.

Neither function turns off the screen itself (with a sufficiently bright external lightsource at a direct angle to the screen the displayed window can still be seen.

I will e-mail intel and see if they have a solution. Apart from their help, are the odds of finding this setting in windows reasonable for an inexperienced windows user?

[MANEMAN]

are the odds of finding this setting in windows reasonable for an inexperienced windows user?

Most definitely. I usually find answers to exotic problems just about the time I am ready to throw the equipment I am working on away due to old age and obsolescence though. :(

If the ablity to lower the backlight in Linux is being done at Kernel level, obviously a Windows solution may be just a tad more difficult. - Just a tad !

(You could try asking Microsoft for the code.)

However, joking aside, any " Problem solver " worth their salt, and trying to help you would be more concerned upon advising you about your primary concerns which would seem to be the area of University study. Therefore a simple way of getting you to view your computer more comfortably would seem to be the main and only objective in this case.

Do consider a screen filter. What are screen filters used for ? - "To restrict glare from the computer screen. Too much glare from a computer screen can be damaging to the eyes (though not permanently), causing eyestrain. More likely, glare can tire the eyes causing discomfort and hindering work. Screen filters reduce glare by interposing an opaque medium."

You will find such filters here and in other areas of the internet: http://www.paperston...en-Filters.aspx

A cheaper alternative would of course be sunglasses. (Polarized not good for LCD screens, but worth a shot on other types of screen) See here: http://www.eyekit.co...-explained.html

There are recorded cases with LED backlighting where it has been found that lowering backlight brightness has actually caused migraine type headaches and has the potential to cause seizures in some individuals due to the fact that the LED's are being voltage / frequency switched to lower the light output.

Lowering glare, (by means of frequency change) although being kinder to the eyes can start to interfere with the human brain operating system as has been reported also by users of energy saving light bulbs (Catch 22 situations every which way we turn !)

• LED-backlights in most laptops do not generate constant light, rather, they flicker (flash on and off, like a strobe light) at a high frequency for most brightness levels.
  
• The flickering of the LED-backlight seems to serve two functions: (1) it saves power, and (2) it is used to control the brightness of the display.
  
• There are a couple of relevant characteristics to the flickering: (1) the speed at which the LEDs are turned on and off (frequency), and (2) the amount of time that the LEDs are off, versus the amount of time that they are on, during each cycle (pulse-width).
  
• The brightness of the display is adjusted by changing (or modulating) the pulse-width, i.e., the LEDs are turned off for more of the time than they are turned on. This makes the display look dimmer.
  
• It would be possible to drive the LED-backlight with circuitry that does not flicker the light, but rather make the LEDs always on. This is not typically used, however, because the circuitry is either more expensive, or less precise.
  
• The flicker of the screen can be verified by viewing the laptop display through the LCD viewfinder of a digital camera. Because the frequency of the camera is not in sync with the frequency of the LED-backlight of the display, the display will appear to flicker through the camera.
  

I read an article a while back on http://hackaday.com where a guy found that LED's actually perform at 70% of their original brightness after about 2,200 hours of use. If this is progressive, - time may eventually give you the level of backlight brightness you require when using Windows.

If you are using Windows 7 only to view silverlight videos as you seem to imply, you could of course install Windows 7 on a VM (Virtual Machine) within the Linux environment, and then you should regain your control of backlight brightness . - The best of both worlds !

Warming the "Whites" can at times be more comfortable. Try this freeware: http://screenwhite.com/screenbright/

If I were you, I would see my University Studies as the first priority, buy myself some tinted sunglasses, knuckle down and get some ruddy work done, and worry about all the other crud when you get to be about my age and have ruined your eyesight looking at CRT and LED screens for most of your working life. :lol: :lol:

Technology + Humour. - Priceless.

John.

[PinkShinyRose]

Thank you for your reaction, by now I have an anwser from medion, claiming it cannot be done in windows. They also advised me not to do it in linux because it reduces backlight lifetime. So looking at a screen filter might be a good idea anyway. I also installed a virtual machine, and then got silverlight to work a little in wine (it does almost nothing, but somehow allows me to watch the video's I needed, so it works good enough for me). So for now the problem is solved. Thank you for your help, I'm not going to put more time into this (except maybe to buy a screen filter).

PS I checked with the camera from my phone, and I don't see flickering in the screen, I do see some strange arched lines on the screen.

[MANEMAN]

Thank you for the reply.

Good luck with your studies.

John.