0

Increasing daytime/outdoor brightness for Seven-Segment LEDs
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Increasing daytime/outdoor brightness for Seven-Segment LEDs

by song123 on Fri May 14, 2021 4:16 pm

Hello,

I have two questions about Adafruit's 0.56" tall 7 segment LED displays and their brightness levels:


1. How many LEDs are in there in each segment in Adafruit's 0.56" tall 7 segment LED number displays?
These are the products I'm referring to: blue and the white.


2. BRIGHTNESS: We are having a hard time viewing this in daytime outdoor brightness. It's very bright at evening/nights, but becomes completely impossible to see at daytime (even in shade in cloudy days). Is it possible to get the 7-segment LEDs to be even brighter?

- Or, does anyone have a suggestion for alternatives (at Adafruit or another company) for even brighter 7-segment displays? How is it that gas stations and pizza stores have those super bright displays that are visible at daytime?

- Or, does anyone have an alternative suggestion for number displays that would be very visible in daylight, even if not seven-segment LED?
We've tried OLED 16-bit Color (1.5" tall) and 18-bit color TFT LCD (2.2" tall) but both were actually not as bright as the LED 7-segment.

song123
 
Posts: 4
Joined: Fri Apr 02, 2021 8:50 pm

Re: Increasing daytime/outdoor brightness for Seven-Segment

by adafruit_support_mike on Sat May 15, 2021 12:28 am

song123 wrote:1. How many LEDs are in there in each segment in Adafruit's 0.56" tall 7 segment LED number displays?

One per segment.

song123 wrote:Is it possible to get the 7-segment LEDs to be even brighter?

Not really.

Increasing the current through the LED will make it brighter, but the LEDs will burn out before they can compete with full daylight. Think about car headlights for comparison.. they run from a 12V supply and are blinding at night, but are almost invisible in full sun. The same is true for sodium vapor street lights, which use even more power.

song123 wrote:- Or, does anyone have a suggestion for alternatives (at Adafruit or another company) for even brighter 7-segment displays? How is it that gas stations and pizza stores have those super bright displays that are visible at daytime?

The LEDs do run bright, but they're also located in places that have some shade, and are oriented vertically so they don't get much direct sun.

Light density varies by about ten orders of magnitude between day and night. We don't really see it because our eyes respond logarithmically.. we see ratios of light density more than absolute values. The closest we get to absolute perception is when we walk from full sun to deep shadow and vice versa. The period where our eyes adjust to the new density gives us a taste of how different the levels are.

song123 wrote:Or, does anyone have an alternative suggestion for number displays that would be very visible in daylight, even if not seven-segment LED?

Put the LEDs behind a piece of dark acrylic. That will block external light and provide contrast for the light from the LEDs.

adafruit_support_mike
 
Posts: 63074
Joined: Thu Feb 11, 2010 2:51 pm

Re: Increasing daytime/outdoor brightness for Seven-Segment

by blnkjns on Sat May 15, 2021 12:51 am

Do you need realtime updates, or is occasional updating OK? ePaper has excellent daylight readability, but changing what is displayed can take a couple of seconds.

The modules have 1 LED per segment.
I did a quick test with a comparable display with TM1637 driver, and the biggest problem IMO in daylight is the segments are pretty reflective, especially the white ones with their yellowish coating. Brightness by itself is enough in my samples, but the "off" segments become similar bright. So they are really helped with some shade.

If you look at raw segment-displays from Mouser, or RS, you see there is some variation, but they never get super-bright. It will probably be caused by the matrixing. The LED can be on for 1/8th of the time max.

Do you have room to make segment displays yourself, for example with Neopixels? 15 neopixels can make a nice segment that is much brighter than regular LED segment displays. You can even opt for the very tiny 2x2mm ones, and make 3-LED segments with them and still have only like 20mm digit height.

I see a product request coming up: chainable boards with 7x3 + 2 Neopixels in the 2020 form factor (2 for decimal point AND comma), and a dual-dot module for time display.
suggestion.png
suggestion.png (11.97 KiB) Viewed 268 times

Sorry about my uber-low-res pixel editor for sketching.

blnkjns
 
Posts: 663
Joined: Fri Oct 02, 2020 3:33 am

Re: Increasing daytime/outdoor brightness for Seven-Segment

by alphanumeric on Sat May 15, 2021 4:55 am

I have a portable setup that see's bright daytime sunlight. It has a Pimoroni Unicorn Hat HD as the main display scrolling text. And an LED Shim that shows info. I have them mounted behind a black diffuser. https://shop.pimoroni.com/products/pibow-modification-layers?variant=1047619725 It made a big difference in readability. It's still hard to read from a distance, in bright sun, but way better than it was without it.
I have my Unicorn Hat and LED shim at half bright in dark conditions. Full bright in daylight. And I switch the text on the Unicorn Hat to White in very bright sunlight. I have that option so I do it. The Unicorn Hat and LED shim have RGB LED's

alphanumeric
 
Posts: 564
Joined: Sun Sep 07, 2014 7:06 pm

Re: Increasing daytime/outdoor brightness for Seven-Segment

by song123 on Tue Jun 01, 2021 12:02 pm

Thank you for your suggestions, everyone. Putting the Seven-Segment LEDs behind a dark acrylic does help a lot. But unfortunately it's really not ideal for our purposes, so we're considering it as one possible option and trying to still see what the other possibilities are.

I do have a follow-up question then:
What exactly are the LCD or OLED screens that are being used in smartphones (iPhones, Androids) that make them visible in full daylight?
Where can I buy similar screen technology products for prototyping?

We tried these Adafruit TFT LCD (https://www.adafruit.com/product/1480) and OLED (https://www.adafruit.com/product/1431) screens, but they were not as bright as the Seven-Segment LEDs (https://www.adafruit.com/product/881) that we tried. And still, the Seven-Segments become nearly invisible/washed out in the daylight, even when cloudy and overcast outside. Are there products at Adafruit or outside Adafruit we can try that is similar to the LCDs/OLEDs being used in smartphones, and closer to that level of daytime brightness?

Thanks so much for your help!

song123
 
Posts: 4
Joined: Fri Apr 02, 2021 8:50 pm

Re: Increasing daytime/outdoor brightness for Seven-Segment

by song123 on Tue Jun 01, 2021 12:09 pm

blnkjns wrote:Do you have room to make segment displays yourself, for example with Neopixels? 15 neopixels can make a nice segment that is much brighter than regular LED segment displays. You can even opt for the very tiny 2x2mm ones, and make 3-LED segments with them and still have only like 20mm digit height.

I see a product request coming up: chainable boards with 7x3 + 2 Neopixels in the 2020 form factor (2 for decimal point AND comma), and a dual-dot module for time display.
suggestion.png

Sorry about my uber-low-res pixel editor for sketching.



This 20mm digit height version with 2x2mm 3-LED segments sounds absolutely perfect for this project! It'd be wonderful, but it's a bit beyond my skill level to try to make it myself. For our project, we just need the decimal point, not the clock colons, like this 88.88
Is it possible to make a product request and how do I go about making the request?? Haha sorry, I'm kind of a Adafruit forum noob here.

song123
 
Posts: 4
Joined: Fri Apr 02, 2021 8:50 pm

Re: Increasing daytime/outdoor brightness for Seven-Segment

by adafruit_support_mike on Tue Jun 01, 2021 7:56 pm

song123 wrote:What exactly are the LCD or OLED screens that are being used in smartphones (iPhones, Androids) that make them visible in full daylight?

They use a combination of techniques.. anti-glare coatings, higher backlight brightness, optical bonding between the TFT and the protective front layer of glass, In-Plane Switched control (which makes the LCD thinner and more consistent), and 'transflective' construction that puts a one-way reflective layer behind the TFT so incident light adds to the displayed image instead of dimming it.

song123 wrote:Where can I buy similar screen technology products for prototyping?

That's where things get difficult.

LCDs and TFTs are generally custom made to the client's specifications. Cell phone manufacturers buy in quantities large enough and regular enough for the display manufacturers to build whole plants to meet the demand. Display quality is a point of competition in the market, so the cell phone manufacturers have no interest in allowing a third party market to exist. They also have no interest in releasing documentation for the displays they buy.

The upshot is that the best displays are mostly available as replacement parts for the devices that use them. Secondary markets do exist.. a display manufacturer with a contract for 100k displays might run production for 105k to guarantee they get 100k deliverable units. Any of the 5k extra units that work can (depending on client approval) be sold as replacement parts or to third parties in general. We buy all our displays on the secondary market because we aren't big enough for primary contracts.

And the closer to the cutting edge a display is, the less likely it is that you'll be able to find documentation for it. In most cases you'll have to try and reverse-engineer its pinout and communication protocols from a working unit of the device it was made for.

song123 wrote:Is it possible to make a product request and how do I go about making the request?

Our products team is always open to new ideas, but there's no guarantee that a requested item will end up in the shop.

adafruit_support_mike
 
Posts: 63074
Joined: Thu Feb 11, 2010 2:51 pm

Re: Increasing daytime/outdoor brightness for Seven-Segment

by plutonic on Fri Jun 04, 2021 4:59 pm

I'm also interested in something like this, and found this thread by search instead of opening a new thread. There was also another one about the 1.1" displays. It does seem to me that there are lots of displays and indicators that really work in daylight, such as sports scoreboards, car taillights and turn signals, etc. They traditionally used little incandescent light bulbs and weren't high tech at all. So maybe it's just a matter of the right diffuser, and using powerful leds instead of filaments these days.

In my case I'd want a 4 digit display with a decimal point, preferably with 10 hz update, basically for sports timing. Maybe I can do it with high powered discrete leds and a diffuser? Anyway I vote yes on the product request. I'd ideally like a segmented daylight display that is pretty big, say about 2 inch digits (1.1" would work though). LED or LCD are both ok, power isn't too big an issue, but e-paper is too slow.

plutonic
 
Posts: 68
Joined: Wed Jan 06, 2016 3:21 am

Please be positive and constructive with your questions and comments.