Sparkfun LCD, ok without backlight, or in sunlight?

Other Hardware Displays
1

Hi all,
I have the Sparkfun 16x2 white-on-black LCD and it works ok, but must always use the backlight. It's also no great on sunny days.

I'm looking for a purely reflective type LCD, or at least one that will work great in sunlight. It would be nice to save on battery power by not using a backlight.

My question are: Does the Sparkfun black-on-green, 16x2, LCD work more like a reflective type (more than the white-on-black one)? Can I use it with no backlight? And is it easily readable in bright sunlight?

Or does anyone know of a good, reflective LCD display that is serial-enabled for Arduino?

Thanks in advance.

2

Can I use it with no backlight? And is it easily readable in bright sunlight?

You can experiment since you already have one. Generally, the positive types (lights going through the pixels, like white-on-blue) don't work without backlight. The negatives (reflective. lights got blocked by the pixels) work without backlight.

Or does anyone know of a good, reflective LCD display that is serial-enabled for Arduino?

Parralex (?) has them. and I am sure New Heaven has them too. However, they are generally quite expensive and it makes more sense (and more fun) to program an avr that functions like a serializer.

3

dhenry:

Can I use it with no backlight? And is it easily readable in bright sunlight?

You can experiment since you already have one. Generally, the positive types (lights going through the pixels, like white-on-blue) don't work without backlight. The negatives (reflective. lights got blocked by the pixels) work without backlight.

I don't have the black-on-green. I only have the white-on-black, which is basically not readable at all without backlight. I am asking if the black-on-green will work with little to no backlight. From what you are saying, it will, thanks.

dhenry:

Or does anyone know of a good, reflective LCD display that is serial-enabled for Arduino?

Parralex (?) has them. and I am sure New Heaven has them too. However, they are generally quite expensive and it makes more sense (and more fun) to program an avr that functions like a serializer.

The ones at parallax look to be very similar to the Sparkfun models, and basically about the same price.

The ones at New Haven also look similar, and maybe slightly cheaper. However, it looks like they are mostly (if not all) RS232 as opposed to TTL. I assume they can run on TTL signal voltages (in RS232 data format). I have an RS232 output algorithm for VFD's, but it would be nice to simply plug and play using the serial library for fast/dirty projects, without re-inventing the wheel.

Does anyone know whether one brand or the other works better with no backlight and/or in direct sunlight?

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I don't know if your white-on-black is similar to my white-on-blue but for my case, I had to keep back light on all the time indoors. But if I turned off the back light, I can see outdoors. I had to readjust the contrast a bit though.

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liudr:
I don't know if your white-on-black is similar to my white-on-blue but for my case, I had to keep back light on all the time indoors. But if I turned off the back light, I can see outdoors. I had to readjust the contrast a bit though.

Thanks. I haven't messed with the contrast outdoors with the backlight off. I'll give that a try.

Also, a friend of mine said he flipped the polarizing screen on some LCD's to get the negative LCD image. Has anyone tried that on these LCD displays? Will it turn my white-on-black into a black-on-white LCD? It looks like it will come apart easily with a few metal tabs.

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Putting it back together is the hard part, not taking it off. The conductive rubber and metal tabs are not very friendly to disassembling and reassembling. Try the contrast first.

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liudr:
Putting it back together is the hard part, not taking it off. The conductive rubber and metal tabs are not very friendly to disassembling and reassembling. Try the contrast first.

I was worried about that. I'll definitely try the contrast first.

8

Ok, I just went and ordered a black-on-green display.

So for anyone else who may have been wondering, the black-on-green display is totally readable in normal lighting without any backlight. By comparison, the white-on-black is almost unreadable without some backlight.

In normal, indoor lighting, the black-on-green display is readable with no backlight at all, in fact, you can't even tell any difference if you turn the backlight on full or not. In darker lighting conditions, the backlight makes a difference as would be expected.

The white-on-black displays are very very dark, and unreadable, in normal indoor lighting with no backlight. I played with the contrast, but it was already set to the best setting. The white-on-black simply is not useable without backlight. It is also not great outside in sunlight. It is probably best used indoors. The darker the environment, the better.

Obviously, if battery power is a consideration, and you have normal lighting, the green-on-black will be a better choice.
Here's some info on the power useage and noise.

On the black-on-green, I measured 3ma without backlight. 14ma with full backlight.
With no backlight, and using a 10uF filter, while powered from a FTDI basic USB cnverter, the noise on the power supply was about 58mv P-P.
With the backlight at 50%, the noise was a 142mv P-P square wave.

On the white-on-black, I measured 3ma without backlight. 19ma with full backlight.
With no backlight, and using a 10uF filter, while powered from a FTDI basic USB cnverter, the noise on the power supply was about 56mv P-P.
With the backlight at 50%, the noise was a 172mv P-P square wave.

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the white-on-black is almost completely unreadable without some backlight.

Looks like your experience contradicts that of liudr. Maybe you can ask where liudr got his lcd so we can find a white-on-blue lcd that is readable outdoors without backlight.

10

I just went and ordered a black-on-green display. In normal, indoor lighting, the display is readable with no backlight at all, in fact, you can't even tell any difference if you turn the backlight on full or not. In darker lighting conditions, the backlight makes a difference as would be expected.

If you get in your DeLorean and go back a few decades you will find out that this is a non-issue since that's all that is available. You wouldn't want to mess with the backlight, most required 150 (One-Hundred and Fifty - not a typo) volts.

Maybe you can ask where liudr got his lcd ...

I believe he gets many of his parts from a surplus house near Niagara Falls*. In that case (or from any surplus house) they might not be completely consistent from one month to the next.

Don

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I got my first and only white on blue from adafruit. It was slow and needs back light in well-lit indoor environmenit I will try to get a picture of it under sun light.

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I will try to get a picture of it under sun light.

You wouldn't be able to do that if you lived here.

Don

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I will try to get a picture of it under sun light.

That, and a picture of the lcd itself (backside?). I am tempted to get 20 of such beasts if I can be sure that it works outdoors without backlight.

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Let me save you the trouble liudr, unless your white-on-blue is a lot different from my Sparkfun white-on-black.

Thanks again, for the input. The black-on-green is going to work perfectly for me.

In direct sunlight,
black-on-green is much easier to read, it is just plain easy to read,
white-on-black requires a little more effort to read at a glance.
In either type, the backlight makes no difference in direct sunlight.

In total darkness,
white-on-black has a brighter result, but is almost too bright at max backlight,
black-on-green is dimmer but totally readable at max backlight.
In total darkness, the white-on-black is much easier to read with minimal backlight, using much less power.

Basically it comes down to:
In the dark, the white-on-black is probably better for saving power.
In sunlight, green-on-black is much easier to read, but there is no power difference since backlight will not matter.
In indoor lighting both are easily readable, but green-on-black will work with no backlight, while white-on-black will require some backlight.

In this composite-photo, the camera makes the ones in total darkness seem a little darker than they are in person. This is just an artifact of my camera. In person the black-on-green is bright enough to read easily, and the white-on-black is a little too bright.

(I also adjusted the contrast on each LCD to optimize each condition, but really, once adjusted, it seemed to be optimized for all conditions without much fiddling. The contrast setting on the black-on-green was far more sensitive to movement of the pot, though. The white-on-black was easier to set)

http://home.comcast.net/~loudgpz/SparkfunLCDcomparison.jpg

15

http://home.comcast.net/~loudgpz/SparkfunLCDcomparison.jpg

Thanks. I certainly hope the two upper-right pictures are not what liudr's meant "visible".

I am still waiting to find out how liudr's lcd does under the sun. Fingers crossed.