Is it possible to improve contrast for a monochrome LCD? - Page 1
Forum section: electronics / projects

author: sam1275
author_rank: Frequent Contributor
timestamp: January 07, 2016, 09:40:48 pm
content: Hi everyone.I have a picoLCD:http://www.mini-box.com/picoLCD-256x64-Sideshow-CDROM-BayIt works good except for the contrast, it's way too low to be read if not read close to it, and most time I cannot even see anything on it further than 1 meter, okay I'm a bit near sighted, but it's much lower even compare to a very low end little color LCD, I tried to adjust by software, but when I turn it up, the pixels that should off are on, so the whole background is showing up, and real contrast is even lower.I think the pixels are not dark enough, and BTW the backlight is too bright, so it go through the "black" pixels to lower the contrast and also disturb my sleep----I have to let it on 24x7.Will the contrast appear higher if I modify the hardware to make the backlight dimmer? Or turn the voltage to the LCD panel higher? How to do it, or any other options?Thank you.

author: wraper
author_rank: Unknown
timestamp: January 07, 2016, 10:14:58 pm
content: Quote from: sam1275 on January 07, 2016, 09:40:48 pmUnfortunately you cannot do anything about this, LCD itself is crap. The only thing you could play with is lowering the brightness of the backlight.

author: station240
author_rank: Unknown
timestamp: January 07, 2016, 11:16:24 pm
content: Does sound like the led backlight is too bright, increasing the resistor(s) that power the LEDs would solve that. Though given the brightness is software controlled, you have to be careful not to alter a resistor for the brightness control instead.Have a look at the PCB itself, perhaps there are some adjustments on there.

author: SL4P
author_rank: Super Contributor
timestamp: January 08, 2016, 01:09:47 am
content: LCDs optical filtering is often constructed for best viewing from specific angles - based on the intended installation. e.g. looking down from 30-degrees in a rack-mounted panel, or from 'below' by 30-degrees for a desk/console mounted display.Then of course, there are completely crappy LCD panels !

author: promacjoe
author_rank: Regular Contributor
timestamp: January 08, 2016, 03:19:07 am
content: You can replace the polarizer sheet that is in between the glass of the LCD, With 1 that is oriented 90° from the original. This will invert the color of the characters. Instead of a white background with black characters, you will get a black background with white characters. This may be easier to see for you. I.e. it will not be flooding your eyes with a bright light.A polarizer sheet can be obtained through a theater supply. you can also salvage one from an old flat screen monitor or TV.

author: sam1275
author_rank: Frequent Contributor
timestamp: January 08, 2016, 02:22:59 pm
content: Thank you everyone.I just ordered an HP POS VFD, I will replace the LCD after arrives...

author: zapta
author_rank: Super Contributor
timestamp: January 08, 2016, 03:12:55 pm
content: Quote from: SL4P on January 08, 2016, 01:09:47 amThis is exactly the case with Fluke 107. If I look straight, contrast is poor. 30 degrees down and its just great.