Type of Monochrome LCD readable under sun light, in door or LED backlight - Page 1
Forum section: electronics / projects

author: Wilson__
author_rank: Frequent Contributor
timestamp: June 14, 2024, 10:41:53 pm
content: Which Monochrome LCD technology type can be used inbright outdoorsunlight,in doornormal lighting andat-nightwith LED backlight?Google says, "Monochrome LCD Panel can be made withTN, HTN, STN, FSTN and VAtechnology. It can be divided into transmissive LCD, reflective LCD andtransflectiveLCD".I have this sound meter with grey display and fit above lighting conditions. I do not know what type it is called?Many thanks

author: Buriedcode
author_rank: Super Contributor
timestamp: June 15, 2024, 01:29:57 am
content: I believe you are correct - "transflective" is the combination of the two. A reflective backing to the LCD that allows you to read it in sunlight (if we ignore glare), but its somewhat transparent so it allows some light to come through so a backlight can be used in low lighting conditions. They're generally as good as reflective in bright conditions, but will absorb a fair bit of the backlight in low light conditions. Thats normally not a problem though since in very low light the backlight doesn't need to be bright at all, and you're better off under-driving them.Note its very rare for transflective displays to be negative transmission, they are almost always positive - so it should be black/blue pixels on white/grey background, as opposed to negative,which is normally black display with pixels allowing light to come from the back. Negative displays always require a backlight.FSTN tech adds a correction film to the display, so that pixels appear "black" instead of bluish, and it improves contrast - it has nothing to do with whether its sunlight readable, but its generally a nicer-to-look-at type. Like the old nokia 3310 phone - that was a classic graphic FSTN and easily read in full sunlight.These days, whilst theres still millions of these types of displays used in many products, it is becoming harder for the hobbyist to find them. Sure there's still thousands of the HD44780 character displays, but the market seems to be flooded with either STN blue (white on blue, needs a white backlight, difficult to read in sunlight, and looks awful) or "green" which are actually VATN displays with a green filter on the back to emulate older STN displays. VATN displays surprisingly have very good contrast and I would think that even without a reflective backing can be read in sunlight easily. Given they are about $3 each, I would buy one and test it yourself if you need a 16x2 character display. The backlights are stupid efficient, needing a few mA to be pretty bright.As for graphic, again, STN/FSTN is still about in 128x32, 128x64 all the way up to 320x240, but have mostly been displaced by TFT and OLED displays and so are harder to find, and expensive.So briefly: FSTN or VA, both provide excellent contrast with VA also having a much wider viewing angle, but transflective is what you want. Definately apositivedisplay, sometimes the white diffuser of the backlight provides enough back reflection to allow it to be fully sunlight readable without it being truely transflective.

author: Wilson__
author_rank: Frequent Contributor
timestamp: June 15, 2024, 11:24:00 pm
content: Sorry, missed attached this photo. I have this sound level meter. Black character on grey background. Readable in direct sun and in door. Can turn on back light as needed for reading at night.

author: soldar
author_rank: Super Contributor
timestamp: June 16, 2024, 12:42:22 am
content: I have several of these panel mounted volt-amp meters bought on eBay and they can be read perfectly in bright light just like calculators, etc. but they also have an LED and can be read in the dark but it seems to me the LED light is not coming from behind but from the sides.

author: uer166
author_rank: Super Contributor
timestamp: June 16, 2024, 03:39:19 am
content: There's also the other option: a reflective display with a front-light (diffused). E.g. sharp memory, or e-ink displays can be combined with a front-light panel and get best of both worlds.

author: Coordonnée_chromatique
author_rank: Frequent Contributor
timestamp: June 16, 2024, 07:35:05 am
content: Quote from: Wilson__ on June 14, 2024, 10:41:53 pmCould you specify the vision angles that you need and the exerior lights flares angles and intensities that you have to face of ?

author: Buriedcode
author_rank: Super Contributor
timestamp: June 16, 2024, 08:29:39 pm
content: Quote from: Wilson__ on June 15, 2024, 11:24:00 pmLikely transflective STN.As others have mentioned, some to crude "side lit" for reflective displays, which is good enough for most conditions, but doesn't ways provide even illumination. If the sound meter you have has no "hot spots", then it could be and EL backlight - which is pretty old school now as most have switched to LED, but if there are bright spots, then thats where the LEDs are.

author: Wilson__
author_rank: Frequent Contributor
timestamp: June 16, 2024, 08:40:18 pm
content: Many thanks. Nothing too specific. Just something normal and average